Contemporary problem essay

For the final paper, consider a contemporary problem and argue (1) that the problem exists, (2) how to solve the problem, (3) that the solution is feasible, and (4) that particular benefits accrue to relevant stakeholders—paying particular attention to rhetorical scope, audience, and logical organization.

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You must cite and reference 3 library-based, peer-reviewed research sources for this project. Use Academic Onesearch, JSTOR, or another database through our library search function.  Do not stop searching once you have found three research sources; find the most appropriate sources for the assignment. You may use additional high-quality sources once that minimum is met.

As with all papers in this course, we will be using proper MLA style, which we will cover in detail in class. Please refer to Owl Purdue for proper guidelines if extra reference is needed. to an external site.

1,250-word minimum requirement (roughly 6 pages double-spaced)

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Australian Strategic Policy Institute


Report Title: Biodata and biotechnology
Report Subtitle: Opportunity and challenges for Australia
Report Author(s): John S Mattick
Published by: Australian Strategic Policy Institute (2020)
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Genomic information is the raw material for genetic engineering.

Genetic engineering, as opposed to the genetic selection practised since time immemorial in the agricultural,
animal breeding and fermentation industries, has its roots in the manipulation of genes in microbial hosts during
the 1970s to produce pharmaceutical products such as human insulin. The technical complexity of genetic
engineering in plants and especially animals is much greater and has largely been limited to introducing gene
sequences that confer viral or insect resistance or disable particular genes, such as those involved in ripening,
to extend the shelf lives of products.

The ease and precision of genetic engineering have been transformed with a discovery that came out of left field
(in another example of the beautiful serendipity of research and how rapidly the landscape can change), in this
case of a viral defence system in bacteria that’s been adapted to allow DNA changes, insertions or deletions in the
genome of any organism.

This system is called CRISPR, an acronym derived from the characteristics that were first noticed in strange repeated
sequences in bacterial genomes.* The technological innovations that have ensued have been extraordinary,144,145
the latest enabling relatively error-free insertion by RNA guide molecules of any desired sequence at any specific
position in the genome (termed ‘prime editing’).146 CRISPR is now being widely used to alter genomic information in
research, human medicine, pastoral animals, agriculture and industrial biotechnology.144,145,147

Human gene therapy and repair
CRISPR prime editing has been shown to correct the genetic causes of the inherited genetic disorders Tay–Sachs
disease and sickle cell anaemia and has the potential to correct the majority of known genetic variants associated
with human diseases.146 There are also other systems, less efficient but nonetheless effective, for gene editing using
engineered sequence-specific DNA binding proteins.

Such genetic repairs are mainly confined to those that are feasible to undertake after birth by, for example, the
reintroduction of engineered blood cells or injection into affected tissues, such as the eye. In many if not most
genetic disorders, the damage is already done, although some are amenable to lifesaving treatments, including
dietary modification or supplementation. It’s possible that in future damaged genes may be repaired in embryos
but, in practical terms, many if not most debilitating monogenic disorders will be simply avoided, once genomic
sequencing is routine, by preconception screening and subsequent embryo selection in at-risk couples to avoid
those that are compromised,† as commonly occurs at present with chromosomal disorders such as Down syndrome.

* CRISPR = clustered regularly interspaced short palindromic repeats.
† Such selection is independent of other characteristics and, at least for recessive genes, doesn’t appreciably change the allele

frequency in the population, which allays concerns about longer term unintended consequences. Genetic disorders in the
heterozygous state confer resistance to diseases, such as cystic fibrosis (resistance to cholera) or sickle cell anaemia and
thalassaemia (resistance to malaria).

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Genetic engineering of virulence or replication genes in human viruses has been undertaken for many years to make
them suitable as gene therapy delivery vehicles148 or attenuated vaccines.149

Ex vivo genetic engineering of patients’ immune cells, notably synthetic ‘chimeric antigen receptor’, or CAR T-cell
therapy, is being used successfully to target antigens present on haematopoietic (blood) cancer cells and shows
promise for solid tumours.150 CRISPR has also been successfully used to eliminate the HIV retrovirus from the
genome in mice,151 and there have been promising results in a human patient.152

There has been one case of so-called germline editing, carried out in China, to alter a gene in embryos to confer
resistance to HIV-AIDS.153 This has been widely condemned and prompted international efforts to restrict human
reproductive engineering.

Our ability to make sensible changes to the human genome, or the genome of any complex organism, is limited by
our currently poor knowledge of genomic information, especially the genetic factors associated with complex traits
such as athletic or musical ability, personality154 and logical or creative intelligence, among the many dimensions of
human biology and diversity. In most cases, we don’t know the identity of the specific genetic variations involved
and, in any case, most have minor effects and operate in networks, in which a benefit in one dimension may be a
handicap in another. While there’s no doubt that humans will ultimately have sufficient knowledge to guide their
own evolution, that day is a long way off, even if it does engender much debate in the interim.

Genetic engineering of microbes, plants and animals
Things are of course simpler in other organisms, but genetic engineering is still largely limited to simple subtractions
or additions of genes or suites of genes.

Gene subtraction includes the deletion of the ‘poll’ gene for horns in cattle,155 the disabling of the myostatin gene,
which negatively regulates muscle growth to increase muscle mass (meat yield) in merino sheep, goats and pigs,156
and the deletion of specific genes in pigs to obtain resistance to viral gastroenteritis157 and porcine respiratory and
reproductive syndrome.158,159

The addition of new capabilities is the ambition of the nascent field of ‘synthetic biology’, or ‘genome printing’,
and is based on the demonstration that complete viral and even bacterial genomes can be assembled in the test
tube and inserted into a blank viral capsid or cell to create a viable organism. This means, in theory, that any new
type of bacteria or virus, with new genetic circuits, can be designed in silico and made viable in any reasonably
well-equipped laboratory. The construction of synthetic animal and plant genomes from scratch is not yet possible,
and may never be possible, although it may be possible to reverse-engineer existing species to recreate extinct ones
or make new ones.

Designer changes can and are being made across the board, with increasing range and sophistication. The addition
of new genetic capabilities has led to the development of new strains of animals, plants, yeasts and bacteria
with better growth rates, new metabolic capabilities and enhanced disease resistance, among many other

Examples include the introduction of the biosynthetic pathway for beta-carotene synthesis in ‘biofortified’ or
‘golden’ rice, bananas* and potatoes161-163 to increase vitamin A content (lack of which causes blindness in an
estimated 250,000–500,000 children annually), and ‘purple’ rice, which has been engineered to produce the
antioxidant compounds found in blueberries,164 although take-up has been dogged by largely irrational campaigns
against genetically modified plants. The introduction of the bacterial insect ‘Bt’ toxin† into cotton, corn and other
crop plants has, in fact, led to massive reductions in insecticide use, with far less collateral damage to other insects
in the ecosystem, and with no evidence of harm to human health or the environment.165 Some 99.5% of cotton

* Developed at the Queensland University of Technology.
† More than 200 Bt toxins are naturally produced by the soil bacterium Bacillus thuringiensis, cultures of which are sprayed on

plants in ‘organic’ farming.

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planted in Australia) is genetically engineered.166 Almost paradoxically, such crops are more ‘organic’ than they
were previously.

Plants have also been engineered for resistance to a wide range of viruses167 and to control ripening (to extend shelf
life), flowering time and plant architecture in many fruit and horticultural species, including tomatoes, strawberries,
apples, kiwifruit, grapefruit, watermelons and cucumbers.168 As with human genome sequencing, China is investing
heavily in genome editing for crop improvement.169

In animals, examples include the introduction into cattle of a gene that confers resistance to tuberculosis170
and the introduction of a growth hormone gene (from Chinook salmon) into Atlantic salmon, which enables the
salmon to grow faster and to reach the same size with 25% less food.171 Trials are underway to insert or modify sex
determination genes to bias sex ratios in the beef and dairy sectors,172 as well as in poultry, silkworms and pest

Such designed modifications increase the efficiency and quality of food production, as well as reducing waste and
environmental damage. The future will also bring a universe of bio-innovations, including bacteria engineered to
produce, for example, spider silk,174 which is stronger per unit weight than high-tensile steel,175 as well as other
biomaterials for industrial and medical applications, such as tissue regeneration.176

National and social security
The immediate concern for national security is the use of genetic engineering for bioterrorism or
state-sponsored harm.

Bacteria can be easily engineered, even in a backyard laboratory, to carry lethal toxins, but they’re difficult to
disseminate and relatively easy to contain.

Not so with viruses. The topic du jour is the concern that the virus that causes Covid-19 may have originated in, or
at least escaped from, a laboratory. That might or might not be the case, but it was almost certainly not designed
there, if for no other reason than that we don’t yet know enough about the idiosyncrasies of the proteins in viruses
that allow them to infect human cells. Therefore, it’s essentially impossible at present to design specific genetic
changes to that end, even if the technology for engineering viral gene sequences is straightforward.

On the other hand, it may be easy to isolate virus variants that can infect humans by selection for growth in cultured
human cells, although this often causes the attenuation of virulence.177 It’s possible to make existing viruses more
lethal by engineering in genes that attenuate immunological responses, although such viruses may also be less

In any event, it’s almost impossible to prevent the spread of new natural, selected or purposely engineered viruses
that have high infectivity, except by national quarantine, which comes at considerable economic and social cost,
and the development of vaccines or treatments, which takes time. As Covid-19 demonstrates, such viruses may
be by far the biggest threat to national security, as broadly defined, and an easy weapon for adversaries that have
different values from ours. The protection against this is the development of rapid-response capability, including the
fast-tracking of vaccines and antiviral drugs.

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Chapter Title: Genetic Modification of Animals: Scientific and Ethical Issues

Chapter Author(s): Jarrod Bailey

Book Title: Animal Experimentation

Book Subtitle: Working Towards a Paradigm Change

Book Editor(s): Kathrin Herrmann and Kimberley Jayne

Published by: Brill

Stable URL:

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© Jarrod Bailey, ���9 | doi:�0.��63/978900439��9�_0�0

This is an open access chapter distributed under the terms of the prevailing cc-by-nc License at the time
of publication.

Chapter 19

Genetic Modification of Animals: Scientific and
Ethical Issues

Jarrod Bailey
Senior Research Scientist, Cruelty Free International, United Kingdom

1 Introduction

The scientific method demands a willingness to correct and integrate previ-
ous knowledge, based on observable, empirical, measurable evidence and
subject to laws of reasoning; yet, it has scarcely been applied to non-human
animal (hereinafter referred to as animal) research. Nevertheless, animal
use in science started declining in the mid 1970s, at least in the United King-
dom, resulting in a drop in the number of animals used approaching 50% be-
tween the mid-1970s and mid 1980s (UK Home Office, 2016)—perhaps a tacit
admission of problematic species differences that render animals poor models
for humans. This trend was, however, reversed with the advent of genetically
modified (GM) animals, animals whose genetic material has been deliberately
altered in some way by insertion, deletion, or substitution of dna. While the
decline in use of non-GM animals continued steeply well into the new millen-
nium, overall numbers have been rising for some time, solely due to increased
utilization of GM animals (Ormandy, Schuppli and Weary, 2009). UK statistics
for 2015 show that more than two million procedures involved the creation and
breeding of GM animals, who were not subsequently used in further research
(around 50% of the total); and there were 720,000 procedures on GM animals
in further experiments, representing 35% of the total animals used in actual
experiments (Hendriksen and Spielmann, 2014; UK Home Office, 2016). Trends
in GM animal use for the rest of the world are difficult to determine due to
different reporting requirements, but they are likely to be similar, with up to
50% of the approximately 13 million animals used annually in research in the
European Union (EU) (Taylor and Rego, 2016), and the estimated 115 million
animals used globally (Taylor et al., 2008).

This chapter aims to summarize and analyze this shift in the use of animals
in experiments and, without being overly technical, to ask critically why GM

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animals have been so embraced in research. Is this justified? Have they fixed
problems with species differences and made animal research more human rel-
evant? Are there still issues with species differences, and to what extent? Does
the new Clustered Regularly Interspaced Short Palindromic Repeats (crispr)
technique help? Can GM animals ever provide data sufficiently applicable to
humans? If so, what are the ethical costs? How much pain, suffering, and death
is involved?

2 What GM Animals Are, How They Are Made, and Problems of
Efficiency and Specificity

The genome—an organism’s complement of genetic material comprising its
entire collection of genes and associated elements—comprises long mole-
cules of dna, present in almost all cells. There are many genes along its length,
each with a defined function(s), and serving as a template(s) for the manufac-
ture of the proteins and enzymes that are the structural and chemical basis
of life. The genes themselves are made up of subunits, called nucleotides, the
exact sequence of which determines each gene’s function. The human genome
contains an estimated 20,000 genes and more than three billion nucleotides.
Between the genes are other regions of dna that serve, in various ways, to con-
trol the expression of those genes, i.e. when the genes are on or off, or to what
degree the proteins they produce are synthesized.

Because our genes are fundamental to many normal biological processes,
they are also at the root of perturbations of these processes that can cause
things to go wrong, resulting in illness and diseases. Genetic studies have,
therefore, been pivotal to much biomedical research, attempting to under-
stand the basis of diseases and what can be done to prevent, treat, and cure
them. Because animal approaches increasingly appear to be of poor human
relevance, due to the very genetic differences that make species dissimilar and
unique, some scientists have modified genes in animals used in experiments
to attempt to overcome these differences and make them more relevant to
human biology.

Broadly speaking, genes may be inserted or knocked in to animals, their
own genes may be deleted or otherwise rendered non-functional or knocked
out, or existing genes may be modified or repaired to alter their function.
Creating GM animals has undoubtedly become more efficient and specific
since their emergence, with the first reports of GM mice in 1974 (Jaenisch
and Mintz, 1974). Much of what is involved is technical in nature, so it will

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445Genetic Modification of Animals

not be discussed in detail here; suffice to say that various methods are avail-
able to introduce the dna of interest—the dna, synthesized in the laboratory,
which will induce the desired genetic modification—into the zygotes (fertil-
ized eggs) or embryos of the animals to be modified. Briefly, it may be injected
into fertilized eggs (pronuclear microinjection) or into embryonic stem cells
(escs or ES cells)—cells in a developing embryo with the capacity to become
one of many different, specialized types of cell—that are removed from an
embryo for manipulation and, subsequently, re-injected into developing em-
bryos. These are subsequently surgically implanted into surrogate mothers, in
which the embryos will develop, as intended, to term and result in live births
of GM offspring. There are many welfare issues throughout this process, which
are described later in this chapter. Initially, the technology was crude, with the
cutting and splicing of dna and insertion of new genes being fairly random
and with concomitant high wastage of animal lives due to its lack of precision
and efficiency. While gene editing in escs improved the process, it should be
noted that, “while it is commonly and frequently claimed that genome editing
has become significantly (perhaps radically) quicker, cheaper, more efficient,
easier to use, and therefore more accessible, care is needed when interpret-
ing these claims” (Nuffield Council on Bioethics, 2016, Section 2.6); “progress
has often been technically challenging […] ES cells have not been obtained for
most species and, even in mice, where the technology is relatively refined, it is
time-consuming, expensive, variable, often highly inefficient, and requires a
special skill set” (Section 1.11 Skarnes, 2015).

One important welfare issue for GM animals, aside from the obvious out-
come of their genetic modification, is the poor efficiency (on-target efficiency),
and associated undesired (off-target) effects, of the process. On-target effi-
ciency has increased and off-target effects have decreased significantly with
the relatively recent discovery of new methods (Hsu, Lander and Zhang, 2014),
especially the rna-guided programable nuclease gene-editing platform,
crispr (crispr/Cas9 system) (see e.g., Chandrasekaran, Song and Ramak-
rishna, 2017). crispr has generated particularly significant excitement, hav-
ing “swept through labs around the world”, at a “breakneck pace [that] leaves
little time for addressing the ethical and safety concerns such experiments can
raise.” (Ledford, 2015, pp. 20–21). This is because, in relation to other methods,
it is less expensive (Ledford, 2015; various components of crispr experiments
can be bought for as little as US$30), less technically challenging, and less time
consuming (Caplan et al., 2015). It, therefore, deserves particular attention.
crispr derives from a bacterial immune system (Fineran and Charpentier,
2012), and has two components: a single guide rna molecule (sgRNA), which

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is specifically designed to seek and bind to precise targets in the genome that
are to be modified; and an associated enzyme, Cas9, which cuts the dna at the
target site and initiates the genetic modification process. Put simply, crispr
causes complete (double-stranded) breaks in the dna at (in theory) specific
targeted sites, which are subsequently repaired by the cell’s own dna-repair

However, the repair process is inherently error prone and generates small
insertions or deletions of dna at the break sites, which can be used to disrupt
gene function or, in the presence of engineered dna molecules introduced ex-
perimentally, to alter the dna specifically at that site. While this method is
generally considered to be much more efficient and specific compared to other
approaches, any accurate, definitive, quantitative estimation of the efficiency
of crispr is difficult to find, as estimates vary considerably and are affected by
many factors, including the nature of the target site and the crispr molecule
used. Generally, the method has improved over time, but there is a strong argu-
ment that crispr remains far from good enough, scientifically and ethically.
One 2017 review reported that “knock-in efficiencies are still low and highly
variable,” with different genetic loci in zebrafish embryos having genes suc-
cessfully knocked in, in 45% and 70% of cases, though only in 1.7% and 3.5%
respectively, with any real precision. Associated successful germline modifica-
tions to produce founder fish for breeding occurred on average just 3.8% of the
time (Albadri, Del Bene and Revenu, 2017, p. 8). Another recent study found
an average of 9.2% of transferred embryos resulted in mouse pups, and an av-
erage of 76% of these had been successfully knocked out for a specific gene.
The generation of pups harboring specific point mutations was lower: 6.5%
of transferred embryos produced pups, though less than 8% of these had the
desired mutation (Nakagawa et al., 2016). In cell lines, mutation efficiencies are
generally higher, though they range from lower than 5% up to 90%, and gene
knock in less than 10% up to 66% (see Bortesi et al., 2016).

Regardless of on-target efficiency, one issue has plagued the creation of GM
animals: off-target effects, or mutations induced by the GM process that are
not intended but affect other non-specific sites in the genome (Fu et al., 2013;
Hsu et al., 2013; Pattanayak et al., 2013). This is a significant scientific and wel-
fare issue, which raises serious concerns over the wider application of genetic
modification in science, medicine, and agriculture (Kanchiswamy et al., 2016;
Kleinstiver et al., 2016). These concerns include: the low birth rates of animals
with the desired genetic modification and the associated high “wastage”, or
animals that may suffer and/or be killed as a result; and many animals who
harbor off-target mutations adversely affecting the animal’s characteristics
(phenotype) (Guha, Wai and Hausner, 2017). Significant off-target dna cleavage

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447Genetic Modification of Animals

and mutation results in toxicity to those cells in which it occurs (Kim et al.,
2009), and their repair causes chromosomal rearrangements, which can acti-
vate genes that can cause cancer (Cradick et al., 2013; see also Cho et al., 2014).
Not surprisingly, “major concerns of off-target mutations have been observed
in medical and clinical studies,” as well (Kanchiswamy et al., 2016, p. 564). This
leads to difficulty in interpreting data but may also cause these animals further
pain and suffering, due to the off-target effects, and death as they succumb to
adverse off-target effects or are killed because they are of no experimental use.

Despite the considerable effort put into improving the situation, the ex-
tent of off-target effects is still a matter of serious debate (Bassett, 2017).
Astoundingly, they are thought to be up to 50% more common than the
desired on-target mutation efficiency, and they may occur at sites quite differ-
ent to the target site, both of which are of serious concern (Fu et al., 2013; see
also Bortesi et al., 2016; Komor, Badran and Liu, 2017). Many computational
approaches to assessing potential crispr off-target problems exist. Though
useful, each is biased regarding the type of off-target sites it may or may not
fail to predict. It is therefore widely accepted that other, unbiased methods
of assessment must be used to help avoid missing off-target effects that may
be seen experimentally (see Bolukbasi, Gupta and Wolfe, 2016; D’Agostino and
D’Aniello, 2017; Tsai et al., 2015). Some crispr experiments show more than 100
off-target mutations, while others appear to show none (Bolukbasi et al., 2016).
Some analyses have suggested little or no off-target activity for some crispr
molecules, though these analyses examined preselected genomic sites only
so are likely to suffer from bias (see Bortesi et al., 2016). Any single technique
will miss off- target sites that others will detect; and, unfortunately, the most
comprehensive method—whole genome sequencing—is technically difficult
and expensive. For example, a rare mutation (0.1% frequency) would require
sequencing 1,500 genomes to give a 95% probability of finding this mutation at
least once (Sluch et al., 2015).

A recent (2017) study attempted to complete a comprehensive whole-genome
analysis to determine the actual prevalence of all off-target mutations in a
crispr-edited mouse, not only the larger mutations, such as insertions and
deletions (indels) of dna but also the smaller, though no less important, single
nucleotide variants (snvs) that are often not sought. Schaefer and colleagues,
reported “an unexpectedly high number of snvs,” in addition to an average of
146 indels, with many of these in known genes (Schaefer et al., 2017, p. 547).
The authors concluded that “concerns persist” over the unpredictable nature
of crispr off-target mutation sites, which were likely to have a detrimental
impact on key cellular processes and would likely manifest in adverse phe-
notypes. This specific issue remains, however, highly controversial. In March

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2018, Schaefer and colleagues retracted their paper—in the face of pressure
from some members of the scientific community working on crispr—on the
grounds that the study results were irreproducible and unsupported by the
data, and the study lacked key controls (Editorial, 2018; Schaefer et al., 2018).
Retraction of this paper does not, of course, remotely prove or even suggest
that crispr is sufficiently free of off-target effects to be safely used in humans.
Most stakeholders who have opined in its wake have urged further progressive,
yet cautious, research to elucidate the situation and stopped short of inferring
an all clear from the authors’ most recent work (Schaefer et al., 2018). With
particular regard to their revision, Schaefer et al. are careful to note (correctly)
that their latest data suggest that, “in specific cases, crispr […] may not intro-
duce numerous, off-target mutations” (Abstract). Others note that this simply
means that the concern over off-target effects “just isn’t perhaps as big as that
initial study suggested.” (Brown, 2018). More generally, all involved appear
to accept that far too little data exist to reach any robust, definitive conclu-
sions about off-target effects associated with crispr, either way. This sensible,
evidence-based view is supported by the many studies that exist, with a full
spectrum of results (such as those referenced in this chapter), that serve only
to rubber stamp the view that this field is young, and the question of off-target
effects is still completely wide open.

Crucially, just before this Volume went to press, this caution was further jus-
tified by a detailed study published in Nature Biotechnology, which showed
that the specificity of crispr-induced genetic alternations had been over-
estimated to date, due to exploration of them being “limited to the immediate
vicinity of the target site and distal off-target sequences” (Kosicki et al., 2018).
The authors’ more thorough and detailed investigations revealed that—in two
different types of mouse cells and a differentiated human cell-line alike—mu-
tagenesis at the target sites was often much more significant than intended/
expected. Instead of the aforementioned small insertions or deletions of dna,
the resulting crispr-mediated genetic alterations were frequently “large dele-
tions and more complex genomic rearrangements”, often extending to many
kilobases. Further, off-target lesions often resulted in “genomic damage”, which
“may have pathogenic consequences.” The important warnings of their con-
clusions bear repeating here: extensive on-target genomic damage is a com-
mon outcome; consequences are not limited to the target locus but will affect
more distal genes; some repercussions may initiate neoplasia (cancer); it is
likely that some cells in each protocol would contain important pathogenic
lesions, some of which would become cancer-causing in time; and others.
Such frequent and extensive genetic damage is and has been undetectable
by  the  means often used to identify it, leading to its under-reporting and
under-appreciation, and so much more comprehensive analysis of the genetic

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449Genetic Modification of Animals

consequences of crispr experiments is warranted and necessary. This may be
of urgent concern due to the fact that six clinical trials of crispr are currently
underway, for various malignancies/cancers, including esophageal, nasopha-
ryngeal, gastric, non-small cell lung cancer, leukemias/lymphomas and other
hematological malignancies (see

Clearly, off-target mutations remain a major issue, with persistent targeting
of unintended genomic loci (Bisaria, Jarmoskaite and Herschlag, 2017, p. 21; see
also Tsai and Joung, 2016), even as steps are taken to mitigate their occurrence
and effects, such as using engineered/modified crispr components (see e.g.
Bayat et al., 2017; Chandrasekaran, Song and Ramakrishna, 2017; Combes and
Balls, 2014; Ding et al., 2016; Guha, Wai and Hausner, 2017). It is widely believed
that the factors controlling crispr’s precision and accuracy “are still not ful-
ly understood,” and obstacles remain on the path to any clinical application
(Jiang and Doudna, 2017, p. 524). “Much remains to be learned regarding the
efficiency and specificity of crispr/Cas9-mediated gene editing in human
cells, especially in embryos.” (Liang et al., 2015, p. 364) It is considered “nec-
essary” to develop methods of detecting off-target mutations that are much
more sensitive (Tsai and Joung, 2016, p. 310); but it is also thought that these
will never be removed completely (Bassett, 2017), and that off-target effects
will still occur often, no matter how high the on-target specificity (Liang et
al., 2015). Off-target mutations remain stubbornly numerous and confounding
in spite of many, multi-faceted efforts to reduce them and their impact; and
this may have serious consequences for the use of crispr, even in laboratory-
based research, where there will be more acceptance of them. This means that
the role of off-target effects in any observations cannot be ruled out, but espe-
cially in clinical settings, where safety is paramount and even off-target muta-
tion frequencies as low as 0.1% can have serious consequences (Tsai and Joung,

Finally, shortly before this Volume went to press, yet another, but differ-
ent, clarion call for great caution came in the form of two papers published
in Nature (Ihry et al., 2018; Haapaniemi et al., 2018). The double-strand dna
breaks created by crispr/Cas9 as part of its mechanism of action activate a
gene called p53, which is known as the “guardian of the genome”—involved
in the repair of dna damage and, if that damage is sufficiently significant, in
apoptosis, or the destruction of the cell containing the damaged dna. It is
because of these functions that p53—a tumor suppressor gene—is known to
be mutated in more than half of all human cancers (Hollstein et al., 1991; Fo-
ronda and Dow, 2018); if p53 cannot carry out its normal activities, damaged
cells may go on to become tumorous (Ferrarelli, 2018). This is an issue because,
as one might expect, p53 blocks crispr/Cas9 activity; and it therefore follows

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that cells that are experimentally modified by crispr, must, thus, tolerate
dna damage, and so must have deficient p53. In selecting for crispr-modified
cells, therefore, one may be selecting for cells that could lead to tumor forma-
tion, which could be clinically catastrophic. As one of the authors opined, “By
picking cells that have successfully repaired the damaged gene we intended to
fix, we might inadvertently also pick cells without functional p53. If transplant-
ed into a patient, as in gene therapy for inherited diseases, such cells could give
rise to cancer, raising concerns for the safety of crispr-based gene therapies.”
(Karolinska Institutet, 2018).

It has been suggested that such cells could be identified and eliminated by
in vitro screening (Foronda and Dow, 2018), but various problems remain. Just
one, single dna break seems to be sufficient to prime p53 activity, and lead to
cell arrest or death (Foronda and Dow, 2018; Ihry et al., 2018), so the problem
may be greater than first thought. Some have inferred or implied that this is a
new discovery, but it is not: almost quarter of a century ago, this was demon-
strated in human fibroblasts (Di Leonardo et al., 1994). Further, crispr-editing
issues were reported in 2016 with some types of cells, including primary and
stem cells (Hockemeyer and Jaenisch, 2016; Carroll, 2018), the latter being the
type of cell involved in one of the recent Nature papers (Ihry et al., 2018)—so
this may be another illustration of lack of caution among some crispr re-
searchers and advocates, and further reason to doubt that due caution and
critical approach are being applied widely enough—particularly as the under-
lying mechanism was not pursued (Carroll, 2018). As stated in a recent, highly
relevant review, “It is surprising that this phenomenon was not recognized
much earlier.” (Carroll, 2018). Because break-induced toxicity has not been de-
tected in all cell types, but also due to it not being seen in some cell types that
do have functional p53, it means that “the induced arrest phenomenon will
have to be tested and addressed for each type of target cell” as “that pathway is
not the whole story” (Carroll, 2018). Finally, while selection is possible in vitro,
it is not an option for in vivo somatic gene correction, in which this would have
serious consequences for animals and humans (Foronda and Dow, 2018).

3 Current and Intended Uses of GM Animals

3.1 Biomedical
Many GM animals are used in basic research with no direct application (for
example, to a particular therapy for a specific disease), but with aims to investi-
gate the functions of particular genes, for example, and the nature of their reg-
ulation. Others are used as specific models for many different human diseases,

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451Genetic Modification of Animals

including multiple infectious diseases, such as hiv, immune system defects,
blood and metabolic disorders, muscular dystrophy, cancer immunotherapies,
among others (Cornu, Mussolino and Cathomen, 2017). Gene therapy inter-
ventions for some of these diseases have already reached clinical trials, such as
hiv/aids therapies (Cornu, Mussolino and Cathomen, 2017); though there are
some serious concerns over potential immune reactions in humans to two of
the most common proteins used in the crispr/Cas9 system. Recent analysis
of human blood samples revealed the presence of antibodies to Cas9 proteins
in 65%–79% of individuals; and around half of all the blood samples harbored
immune cells with the potential to destroy human cells, containing one of the
Cas9 proteins (Charlesworth et al., 2018). The potential severity of any immune
reaction in patients is unknown, but it could range from making crispr non-
functional, to dangerous inflammatory reactions.

Efforts are being made to use crispr to deactivate and render some
viruses non-infectious and/or non-pathogenic, such as hepatitis B and C viruses
and hiv (Doerflinger et al., 2017; Huang et al., 2017; Li et al., 2017; Moyo et al.,
2017; Soppe and Lebbink, 2017). Serious caution has been advised, however,
due to the risk of causing mutations that increase, rather than decrease, viru-
lence (Wang et al., 2016). It is claimed that crispr holds the key to translating
data from rodent models of psychiatric disorders and neurobehavioral traits
to humans, including disorders associated with anxiety, mood, and substance
and impulse-control (Baud and Flint, 2017, p. 373). crispr’s potential for can-
cer biology has been expounded, as it can recreate potential cancer-causing
mutations identified in human tumors, in both cell lines and GM animals
(Guernet and Grumolato, 2017). Some GM animals are used in attempts to pro-
duce medically important proteins, for example, in cows’ milk, which can be
generated in high volumes and purified from the milk for clinical use. Examples
include treatments for some blood disorders, osteoporosis, and emphysema
(Moura, Melo and de Figueiredo Freitas, 2011). GM animals are central to
efforts to use animals as a source of organs for human transplantation (xeno-
transplantation), targeting biological pathways involved in immune rejection
of transplanted organs.

3.2 Farm/Food Animals
A major application of GM technology (GM also can mean genetic modification
or manipulation, as well as genetically modified) is the engineering of animals
used for food (Ledford, 2015). Examples include, chickens producing only fe-
male offspring for egg-laying, cows producing only male offspring for better
meat yield, pigs who can be fattened with less food, cashmere goats producing
more meat from greater muscle mass and longer hair for greater wool yield;

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and efforts to facilitate greater stocking density, such as cattle without horns
and animals with greater resistance to disease (see Frewer et al., 2013; Nuffield
Council on Bioethics, 2016). Double-muscled pigs (Cyranoski, 2015), rabbits (Lv
et al., 2016), sheep and cows (Proudfoot et al., 2015; Luo et al., 2014) have been
created for human consumption, though many died early and were unhealthy,
and birthing difficulties occurred due to their size (Cyranoski, 2015). Cows with-
out horns can be housed more densely with lower risk of goring injuries (Loria
K, 2016; Carlson et al., 2016). While there may be welfare benefits— millions
of cattle would no longer need to be dehorned, which can be very painful—
they would be farmed more intensively and have less space to live in, further
compromising their welfare. Other efforts include cows that produce milk that
does not induce allergies in humans (Yu et al., 2011); milk with altered fatty acid
content, and milk that contains high levels of lactoferrin (Yang et al., 2008a);
cows who produce “tastier beef” because their flesh contains more fat (Guo
et al., 2017); and pigs who bleed out more efficiently at slaughter (Hai et al., 2014)
and have omega-3 fatty acids in their flesh (Lai et al., 2006). GM salmon, modi-
fied so that they grow at twice the rate of normal salmon and can be housed
in tanks on land, have been approved for human consumption in the United
States (US) (Connor, 2015). Much of this is undoubtedly the result of lobbying
by vested interests that stand to profit from these projects, who assert that, for
instance, the Earth’s growing population and shifting appetites will necessitate
considerable increases in food production that cannot be achieved by any other
means alone; yet, there is strong counter evidence and opinion that alterna-
tive strategies could meet that need, such as reducing food wastage; changing
consumer demand and preferences for meat, dairy, and eggs; and improving
farming and production methods by other means (High Level Panel of Experts
on Food Security and Nutrition, 2014). Despite the potential for both direct and
indirect effects on animal welfare in this area, it is acknowledged that too little
attention has been devoted to the genetic modification of “farm animals” and
to the regulation of the practice (Nuffield Council on Bioethics, 2016).

However, the creation of GM animals commonly used for food is not lim-
ited to making them easier to manage or more profitable for their meat and
milk. Pigs are touted as being more appropriate models of human diseases
than mice, for example, for cystic fibrosis, cancer, diabetes, neurological disor-
ders, high cholesterol, and muscular dystrophy; while a gene associated with
achondroplasia has been targeted in cattle (Carlson et al., 2012; Petersen and
Niemann, 2015).

3.3 Dogs and Monkeys
Concerns that less strict regulations in countries outside of the EU and the
US may lead to GM projects that may not be approved elsewhere appear to

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453Genetic Modification of Animals

have substance. Prior to crispr, a Chinese group created transgenic dogs who
emitted red fluorescent light (Hong et al., 2009). This was far from efficient. 344
embryos transferred to 20 surrogate mother dogs, resulted in seven pregnan-
cies and six live births. More recently, another Chinese laboratory created GM
dogs using crispr, knocking out a gene controlling muscle growth, resulting
in dogs who were “much more muscular” (Doane, 2016; Zou et al., 2015). Their
work was defended via a tenuous link to the creation of future dogs who could
model, for example, Parkinson’s disease; but only two of 60 edited embryos
were “successful.” Elsewhere in China, GM monkeys have been created with
apparently similar characteristics to autism. Eight macaques (out of “dozens”
of GM embryos) were born with a gene (MECP2) linked to autism in humans,
who showed signs such as running “obsessively in circles”, ignoring their peers,
and grunting anxiously when stared at (Cyranoski, 2016b; Liu et al., 2016; Snow-
don, 2016).

Interestingly, when espousing the use of “large animals” as GM models for
human diseases, those who may otherwise stoutly defend GM mice are open to
criticizing them. For example, one recent paper, authored by scientists creating
GM livestock, noted that “the drawbacks of using rodents to model humans
are well established […] mice make poor models for reproductive physiology,
pulmonary problems, metabolic regulation, and many other fields of inquiry”
(West and Gill, 2016). Unfortunately for such advocates, as discussed in this
chapter and in works referenced in it, it appears that “larger animals”, GM or
not, remain poor models for these areas and more, and can only ever be so.
This is compounded by the same, or even greater, confounding issues of low
efficiency and a variety of limitations and complications (see section on non-
human primates, nhps, below).

4 Suffering, Welfare, and Ethical Issues with GM Animals

Many animal researchers acknowledge that creating GM animals involves suf-
fering at every step, from generating sufficient eggs to embryos for modification,
through to the pain and suffering experienced by many progeny (Laboratory
Animal Science Association, 2008; Robinson, Jennings and Working, 2004).

4.1 Breeding and the GM Process
Producing eggs for the embryos used in the GM process involves drug-induced
superovulation of females, whose fertilized eggs are collected post-mating,
which may involve killing the females, a common practice in rodents, or at
least surgery under general anesthesia (more “valuable” species). Approved
killing methods for rodents are, commonly, neck dislocation or carbon dioxide

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suffocation, which can both (not surprisingly) cause distress (Robinson et al.,
2004). Both superovulation and fertilized-egg collection can cause discom-
fort, stress, and post-operative pain (Camara, et al., 2008). After modification,
embryos are implanted into surrogate mothers in the form of pseudopregnant
females, who have been previously mated with vasectomized males (The Boyd
Group, 1999). Pre- and post-natal death of offspring may be significant. One
report showed that an average of just 29% of implanted embryos survived to
weaning, and only a quarter of these (7% of implanted embryos) (Hubrecht,
1995), or an average of 15% ( Robinson et al., 2004), may be GM. Miscarriages
may cause pain and distress, and such poor efficiency means that many donor
and recipient animals must be used to produce a relatively small number of
desired GM individuals. Genotyping of resultant offspring may involve blood
sampling or tissue biopsy. Invasive methods are still common, including tail
snipping, ear snipping/punching, or even toe amputation, all causing pain
in mice (Robinson et al., 2004). The genetic modification process has been
documented, at least in larger animals, such as sheep and cattle, as a factor
in increased gestation length, greater body weight, risk of dystocia (difficult
birth), and various perinatal anomalies and loss. In mice, there is also evidence
of increased embryonic and fetal loss (Camar et al., 2008).

4.2 Animal Lives Wasted
The persistent inefficiency of the GM process is a serious welfare issue (Boyd
Group, 1999; Camara et al., 2008; Laboratory Animal Science Association, 2008;
Robinson et al., 2004). It is difficult to quantify, as many countries do not re-
quire the reporting of GM-animal statistics (Taylor et al., 2008). In the UK, sta-
tistics indicate a high degree of wastage (around 50% of a total of more than 4
million animal procedures in 2015, involved the creation and breeding of GM
animals not used in subsequent experiments), and specific GM license appli-
cations are revealing: seven projects from 2014–2015 proposed using a total of
almost 27,000 animals ( UK Home Office, 2014).

4.3 Effects of Genetic Modification
Inserted genetic material may have adverse effects on GM embryos/animals.
Some may be unpredictable, such the aforementioned off-target effects; while
others are expected and the result of on-target effects, such as GM mice who
will develop painful cancers. Naturally, the GM process may not necessarily
adversely impact welfare; but the critical point is that, frequently, the welfare
consequences of the GM process cannot be predicted in detail, nor can they
be assessed properly. Welfare assessments are by their nature wide open to
subjectivity and opinion, and much more research needs to be done in this

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455Genetic Modification of Animals

area to increase objectivity, if indeed this is possible to any significant degree
(Hawkins et al., 2011, Wells et al., 2006). Therefore, it is acknowledged that
reduced viability or impaired health may be expected (Bundesamt für Veter-
inärwesen, 2006); while some estimates suggest around 20% of GM animals
suffer minor discomfort, 15% severe discomfort, and 30% increases in mortality
and susceptibility to disease (Thon et al., 2002).

Indications may include, for instance, developmental abnormalities, such as
cleft palate; perinatal and post-weaning mortality; skeletal abnormalities, in-
cluding malformed limbs; discharge from eyes and ears; diarrhea; poor posture,
gait, and ataxia; stereotypies, such as lack of alertness, poor or over- grooming,
circling in cage; absence of teeth; poor mothering; poor thermoregulatory
ability; enhanced growth of tumors and development of metastases, often at
atypical sites; increased aggression; seizures; a range of diseases, including dia-
betes, osteoporosis, degenerative joint disease, inflammatory bowel disease,
and ulcerative colitis; sensory and locomotor abnormalities affecting sight,
hearing, smell, balance, and social interactions; and increased incidence of
infectious disease (Dennis, 2002). GM mice databases reveal progressive hear-
ing loss and deafness; development of diabetes; impaired movement and
coordination, including tremors and involuntary movements, difficulty in ini-
tiating movement, abnormal posture, and paralysis; susceptibility to infectious
disease; colitis; progressive muscle weakness; kidney inflammation; premature
death; intestinal obstruction; respiratory distress; hyperactivity; heart failure;
internal bleeding/brain hemorrhage; self-harm; seizures; vision problems and
blindness; and many more (e.g., Mouse encode Consortium, mouseencode.
org; Mouse Genome Informatics, mgi, database, The
Mouse Genome Informatics (mgi) database lists mice under the following cat-
egories (among others): with abnormality of blood, connective tissue, head or
neck, limbs, metabolism, prenatal development/birth, cardiovascular system,
digestive system, ear, eye, genitourinary system, immune system, musculature,
nervous system, respiratory system, skeletal system, and cancers. The scale
of this must also be mentioned: as of July 2017, the mgi database cites 51,000
mutant alleles in mice, with more than 3,100 human disease models; the Inter-
national Mouse Strain Resource ( lists around 40,000 strains as
available worldwide; the International Knockout Mouse Consortium has gen-
erated around 5,000 mutant mouse lines (Rosen, Schick and Wurst, 2015); and
the International Mouse Phenotyping Consortium intends to generate 20,000
knockout mouse strains ( (Koscielny et al., 2014).

Off-target modifications may induce mutations that abrogate gene function
and/or cause rearrangements of the genome with other, subsequent muta-
tional effects on other genes. In assessing effects of GM on welfare, it has been

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cautioned that setting a “normal” baseline must be done carefully. For example,
it is normal for GM mice engineered to have vestibular abnormalities to spend
much time circling in their cages. This may be normal for these mice but should
not be considered normal from a welfare perspective (Hawkins et al., 2011).

4.4 Increasing Numbers of GM Animals
Many of these welfare issues are not exclusive to crispr and exist for other
GM methods. It has been argued that crispr should mitigate many of these,
with its simplicity and greater efficiency, and so should be welcomed by ani-
mal advocates. To some extent this may be true, in time. However, the corol-
lary gives great cause for concern, that this simplicity and efficiency will also
“not only increase in the range and diversity of transgenic rodent strains but
will greatly expedite transgenesis in other species, including non-human pri-
mates” (Combes and Balls, 2014, p. 137). In this regard, crispr is described as a
mixed blessing (Hendriksen and Spielmann, 2014); and animal ethicist Bernard
Rollin (2015) accepts that easier GM techniques would undoubtedly lead to an
increase in the number of animals used “as more researchers engage in hither-
to impossible animal research”. It has been said that crispr will revolutionize
mouse genetics by reducing the time it takes to create a new GM model from
years to months, or even weeks (Fellmann et al., 2017). In other words, for any
reduction and refinement in any specific GM experiment due to crispr, a
greater overall number of GM experiments will offset this, compounded by
more experiments on a wider range of species, including dogs and monkeys.

This is not mere speculation. Aside from being logical, and in addition to
multi-stakeholder enthusiasm for crispr and associated market projections,
it is clear from current scientific literature. Many speculative claims for crispr
reflect an excitement that, in part, is responsible for the great expansion of
interest in the technology and in the creation of greater numbers of GM ani-
mals in academe, biotech firms, and large pharmaceutical companies (Cor-
nu et al., 2017). For example, it is estimated that by 2021, the GM market will
be worth US$6.28 billion (MarketsandMarkets, 2017). It has, therefore, been
strongly suggested that the welfare consequences of genetic modification
for all species should be monitored and explored in greater detail. Perhaps,
at least, an in-depth, systematic, critical assessment of the rationale for using
GM animals in human disease research is warranted; and projects involving GM
animals  should be approved only in “extremely exceptional circumstances”
(Combes and Balls, 2014, p. 143; see also Mepham et al., 1998). Unfortunately,
interest in crispr is, at least for now, manifesting in substantial animal use.
The scientific literature shows (as of June 2017) more than 6,000 publications,
up from fewer than 4,000 just a year earlier (June 2016), and just over 600, 18
months prior to that (Nuffield Council on Bioethics, 2016).

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457Genetic Modification of Animals

4.5 Increasing Numbers of Non-Human Primates (nhps)
There is, therefore, great, well-founded, concern that this interest will trans-
late into greater creation of GM monkeys (e.g. Liu et al., 2014; Niu et al., 2014).
Examples of GM primates have already been mentioned (Cyranoski, 2016b;
Liu et al., 2016; Sasaki et al., 2009; Snowdon, 2016), following on from, for ex-
ample, the first reports of GM macaques in 2001 (Chan et al., 2001), and a GM
nhp model of Huntington’s disease (Yang et al., 2008b). Some scientists are
calling for further increases. To illustrate, a 2016 paper lamenting the failure
of animal research (including nhps) to translate to a greater understanding
of human brain disorders and their treatment—largely due to “lack of good
animal models” and “profound differences in brain and behavior” between
humans and nonhumans—puts its weight firmly, and speculatively, behind
GM nhps as a solution (Jennings et al., 2016, p. 1123). Associated suffering is
justified by a brief assurance of veterinary oversight and intervention. While
accepting that greatly expanding GM nhp creation and use is challenging in
many ways, the authors propose a “concerted international effort” to over-
come those challenges (Jennings et al., 2016, p. 1128), involving automated
methods for training the animals to comply with the researchers’ demands,
chronic use of intracranial electrodes, and the creation of an international
network of nhp centers and vendors. Overall, a horrifying vision for animal
advocates, and scientifically unjustifiable in any case. My colleagues (at Cru-
elty Free International, and indeed in the wider animal protection commu-
nity) and I agree that there is a “dismal record of drug development for neuro-
logical and psychiatric disease over the past several decades” and that “basic
neuroscience has failed to deliver substantially new and effective treatments
for many brain disorders, partially because the animal modelling was done in
species whose brains are too dissimilar from those of humans” (Jennings et al.,
2016, p. 1128). However, we believe that modifying a gene or two in these poor
models cannot overcome these problems or lead to research that is any less

GM nhp creation also suffers from the same problems as GM rodents, even
16 years after the first GM monkey was born (Chan et al., 2001); and so, wide-
spread, efficient, successful, generation of human-relevant GM nhps may be
a forlorn hope anyway (Luo, Li and Su, 2016). Surprisingly little analysis had
been done of this until recently. Though crispr has intensified the genera-
tion of GM nhps, targeting efficiency in nhps is still low, “successful gene
replacement in monkeys via the cripsr/Cas9 system remains elusive, possibly
due to the complexity of dna repair mechanisms in monkeys” (Luo et al., 2016,
p. 242), and “there are still some technical limitations for its use in non-human
primates” (Guo and Li, 2015). A 2017 report acknowledges “the incidence of
undesirable outcomes has not been well characterized”. It states: “Most studies

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experienced very high rates of developmental arrest (can be 90%) … [which]
further raises concerns about non-genetic technical factors contributing to low
rates of survival” (Midic et al., 2017, p. 4). While this study claimed that the cre-
ation of GM nhp embryos could be 80%-100% efficient, this does not reflect on
the efficiency of generating otherwise healthy adult nhps with desired genetic
modifications, and without confounding and/or welfare- compromising off-
target effects. The same study suggests that mosaicism (where offspring con-
tain cells with different genes/gene variants) is “substantial” and is “a significant
limitation,” and accepts that the creation of GM nhps to date was “achieved at
a very high cost in terms of the number of embryos used,” due in part to the
“very limited (around 10%) viability of transferred embryos to term” (Midic
et al., 2017, p. 15; see also Chen et al., 2015). They conclude that inefficiency
remains “a major barrier to practical use of the technology in nonhuman pri-
mates” (Midic et al., 2017, p. 15); and that the entire process is financially costly.
To illustrate, one effort to generate GM nhps via crispr, with two disrupted
genes, reported that of 22 embryos injected, 15 (68%) survived culturing, while
on average just over one third of these contained the desired modification (Niu
et al., 2014). Subsequent attempts to generate GM monkeys involved injecting
186 zygotes; 83 (45%) were transferred to 29 surrogate females, establishing 10
pregnancies (34%), with 19 fetuses. The paper was published while 8/10 were
still pregnant; one miscarried, and the other gave birth to twins, whose genes
had been successfully modified, though mosaicism was confirmed, and pheno-
type had yet to be established.

This is all of particular concern because experimentation on monkeys is
opposed much more strongly than on rodents (Aldhous, Coghlan and Copley,
1999; Animal Aid, 2003; Clemence and Leaman, 2016; Leaman, Latter and Clem-
ence, 2014; tns Opinion & Social, 2010); and genetic manipulation of “higher”
organisms evokes stronger concern from the public (Olsson and Sandøe, 2010).
The European Science Foundation’s European Medical Research Councils
group has stated: “Whether a species needs special protection should not be
based solely on its phylogenetic relations to humans, but on its potential for
suffering. nhps are distinguished by the very advanced nature of their social,
cognitive, sensory, and motor functions” (Olsson and Sandøe, 2010, p. 185).

5 Failure of GM Animals and Consequences for Animals
and Humans

Much has been published on the failures of GM animals to live up to their prom-
ise, though criticisms of GM animals are frequently understated, couched, for
example, as follows: they do not always accurately reflect the human condition;

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459Genetic Modification of Animals

they have limitations; data must be interpreted carefully; and so on. Examples of
failures are numerous, and include Parkinson’s and Alzheimer’s diseases, cystic
fibrosis, type i and type ii diabetes, amyotrophic lateral sclerosis, Kallmann’s
syndrome, Lesch-Nyhan’s disease, ataxia-telangiectasia, sickle-cell anemia,
deafness, visual defects, Duchenne muscular dystrophy, Down’s syndrome, and
schizophrenia (Pratt et al., 2012), multiple sclerosis, cancers, and immunothera-
py (Ruggeri, Camp and Miknyoczki, 2014), migraine (Storer, Supronsinchai and
Srikiatkhachorn, 2015), pain (Craig, 2009; Mogil, 2009), and depression (Benatar,
2007; Bhogal and Combes, 2006; Davis, 2008; McGonigle, 2014; Norgren, 2004;
Webb, 2014). It is, however, increasingly acknowledged in scientific literature
that GM animals are failing to deliver by any measure. For example, GM-based
“advances” in animal models of many human conditions and diseases “have not
made a significant increase in improving the rate of success in Phase ii proof-
of-concept studies”; in other words, GM animals are not leading to more, bet-
ter, safer drugs and indeed may well be hindering the process because they are
misleading (Hunter, 2011, p. 1). GM-animal models of cns disorders “have been
increasingly criticized in the wake of numerous clinical trial failures of nces
[new chemical entities, or new drugs] with promising preclinical profiles”
(McGonigle, 2014, p. 140), and they are “criticized for their limited ability to pre-
dict nce efficacy, safety and toxicity in humans” (McGonigle and Ruggeri, 2014,
p. 162). Clinical trials of gene therapy for heart failure and muscular dystrophy,
despite early promise, have failed (Hulot, Ishikawa and Hajjar, 2016; Lu, Cirak
and Partridge, 2014). And despite many years of substantial effort in the field of
xenotransplantation, and early promises that successful transplantation of pig
organs into humans would be realized by 2010 and worth multiple billions of
dollars, the most recent developments claim no more success than a GM pig’s
heart surviving in a monkey for 51 days (Johnston, 2016), or in the abdomen of
a baboon in addition to its own heart for just over two years, until they were re-
jected when immunosuppressive drugs were reduced (Mohiuddin et al., 2016;
Servick, 2016).

Attempts to overcome other significant hurdles continue, such as porcine
endogenous retrovirus (perv) in pigs, which can cause problems in humans
(Yang et al., 2015); but there remain persistent issues, such as immune rejec-
tion; transmission of infectious agents; ethical problems and boundaries; as-
pects of physiological compatibility, such as discrepancies in coagulation and
metabolism; and others (Niemann and Petersen, 2016). Some argue xenotrans-
plantation is not needed anyway. Prevention of much of the need for trans-
plantation via education and health measures, improved donor recruitment,
and mandated choice and presumed consent/opt-out schemes, and others
have all had positive outcomes in countries that have adopted them (Perera,
Mirza and Elias, 2009).

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With specific regard to crispr, there is also evidence to question claims
that it can improve matters and facilitate more accurate and human-relevant
models. An approach utilizing Morpholino oligomers (MOs) has been widely
used to investigate gene function in zebrafish, but attempts to confirm findings
for specific genes using crispr have been extremely confounding. One study
reported that most genes altered by crispr failed to show similar phenotypes
to experiments that altered the expression of the same genes using MOs, which
the authors attributed to differing off-target effects from the techniques (Kok
et al., 2015). This is mirrored in a study comparing selected genes affected by
crispr and a gene-silencing method using short hairpin rnas (shRNA). These
methods were found to have similar precision; but each affected “numerous”
genes that the other did not, attributable to differences in off-target effects
and in the timing of each (Morgens et al., 2016). To illustrate, a recent study
revealed that previous research implicating the melk gene in certain breast
cancers—with sufficient certainty to prompt pharmaceutical companies to
develop drugs to block its activity, some of which proceeded to human trials—
may be unreliable. When the melk gene was knocked out using crispr, can-
cer cells multiplied unexpectedly, and drugs that targeted melk still stopped
their growth. This casts doubt on the role of melk, and suggests that drugs
targeting melk work through other targets (Lin et al., 2017).

It is often, perfectly reasonably, asked if such failures may be balanced
against any successes of GM technology. This is not the purpose of this chapter,
which is to highlight issues and caveats with it and to supply a more critical ar-
gument against its use. However, any claimed successes, in which it is implied
that the use of GM animals has resulted directly in human benefit, must fulfil
the following criteria: data from the GM animal experiments must be reliably
and sufficiently translatable to humans; these experiments must have provid-
ed data that could not have been obtained in any other way; and these data
must have been critical to the ultimate human benefit. Even if, for the sake
of argument, one assumes such examples exist, they still must be balanced
against an objective appraisal of the scale of failure and against the ethical cost
of the animal research involved.

6 Reasons for These Failures

Reasons proffered for this scale of failure include the evolutionary distance
of humans and non-human species—approximately 65 million years for
humans and mice—and all consequent differences in gene complement
and expression, the artificiality of induced diseases, and the inbred strains of

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animals often used (Davis, 2008). See also two comprehensive reviews of ge-
netic differences between humans and chimpanzees (chimpanzees were used
in science in the US until very recently), and humans and monkeys (Bailey,
2011, 2014). Even with current knowledge, limited because such differences
have barely been sought, they are much more widespread and extensive, with
significant and varied consequences, than is generally accepted. There are sig-
nificant differences in gene complement, but more importantly, in gene ex-
pression, i.e., how these genes are regulated and used in the organism, even
where they are common to both species. These differences affect all biologi-
cal systems, but notably the immune system, the brain, and the liver, which
are fundamental to much biomedical research involving infectious agents and
disease, autoimmunity and inflammation, neuroscience and neurological dis-
eases, and drug safety and efficacy. It is these differences that underpin the
failures of animal research, whether GM or not, discussed in this chapter.

Of course, genetic differences between humans and nhps, as appreciable as
they are, are not as great as those between humans and mice, who constitute
the greatest numbers of GM animals used in science. These differences have
not yet been elucidated in detail, but illustrative examples exist. For example,
a systematic comparison of the mouse and human genomes has revealed that
there is significant conservation of functional genes themselves, with around
half of human dna aligning with mouse dna when directly compared; how-
ever, this of course means that half of it does not. Furthermore, there are,
crucially, “wide ranging differences” in many biological pathways and cellular
functions, which show “considerable divergence”; and the areas of the genome
that control and regulate gene expression are substantially different (Yue et al.,
2014, p. 355). Indeed, many disease-causing mutations are in these areas, rather
than in the main protein-coding parts of genes themselves. Because these dif-
fer, particularly between species, this can make direct animal-human compari-
sons not just difficult and uncertain, but impossible (Bassett, 2017). Even when
humans and mice share genes, they can show functional differences: a study
of 120 genes that are known to be essential for life in humans, revealed that
almost one quarter of them are not essential for life in mice (Liao and Zhang,

The problem with a shift toward GM nhps, in the hope of greater human
relevance, is that there is little or no evidence to support this, even if nhps
are evolutionarily less removed from humans. While it is true to some extent
that nhps “are genetically and phenotypically closer to humans, particularly in
regards to anatomy, physiology, cognition, and gene sequences,” it does not fol-
low that they are, therefore, “optimal animal models for genetic modification
in an attempt to understand human biology” (Luo et al., 2016, p. 241,). This is

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only valid if this results in better translation of nhp data to human benefit.
I argue that it does not, because there is simply no evidence that it does.

One positive for animal advocates, while reading myriad literature on the
burgeoning creation of GM animals, is that there now appears to be more hon-
esty about, and criticism of, the human relevance of non-GM animals. A paper
in the prestigious journal, Nature, cited the wholesale failure of new drugs to
treat amyotrophic lateral sclerosis (als), a fatal neurodegenerative condition,
known as Lou Gehrig’s or motor neuron disease, despite success in animal
models of the disease, as well as similar failures in Alzheimer’s and cancer,
among others (Perrin, 2014). Contemporary criticisms of animal research are
welcome because they have been scant from the scientific community for
decades. Ironically, many criticisms are akin to those made by animal advocates
for many years, which were roundly dismissed. What seems commonplace,
however, is the unfortunate and groundless assertion that genetic modifica-
tion will instantly make failed animal models more human relevant. Evidence
suggests otherwise.

7 Alternatives to GM Animals—The Way Forward

If not GM animals, what is the way forward to understand the myriad human
diseases and realize treatments and cures for them? Modeling human diseases
in cultured human stem cells continues to take great leaps forward and will
surely become a mainstay of biomedical research that “could rival the use of GM
mice in popularity” (Musunuru, 2013. p. 901). Somatic cells (cells from various
parts of the body, other than reproductive cells, such as sperm and eggs, often
skin biopsies or blood) can now be reprogrammed to act as cells in early-stage
embryos, able to develop into many different specialized cell types (Takahashi
et al., 2007; Takahashi and Yamanaka, 2006). Immense collaborative efforts
now collect and characterize cells from many thousands of healthy and dis-
eased human individuals, many with a wide variety of disorders, and use these
induced pluripotent stem cells (iPSCs) for comparative studies of normal and
diseased states and screening of potential new drugs and therapies, including
the study of polygenic disorders (diseases involving many genes). The develop-
ment of 3D cell cultures and organoids (cultured miniature organs) is likely to
increase the in vivo relevance of this approach, with more faithful and accurate
cellular phenotypes (see Bassett, 2017). Organoids successfully developed to
date include, brain, intestine, stomach, salivary gland, esophagus, pancreas,
liver, breast, lung, prostate, fallopian tube, and taste bud (see Driehuis and Cle-
vers, 2017). Genetically modifying such iPSCs and organoids adds another level

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463Genetic Modification of Animals

of sophistication, allowing potential causative gene variants or mutations to
be introduced for further study, for example, to validate mutations implicated
in causing disease and/or for attempts at repairing faulty genes.

Cell lines for these studies have been generated for many diseases, includ-
ing Parkinson’s, Alzheimer’s, Huntington disease, various immune disorders,
cardiomyopathy, and cystic fibrosis (Brookhouser et al., 2017; Nishizaki and
Boyle, 2017); and efforts at repairing mutated genes in these systems have been
promising in, for example, cystic fibrosis and cancers (Driehuis and Clevers,
2017), and retinopathies (Quinn, Pellissier and Wijnholds, 2017). The combined
use of genome editing and iPSCs offers the ability to study genes and muta-
tions in different human genetic backgrounds, which is especially important
for the study of complex neurological disorders. This approach has been found
to “closely mimic cellular and molecular features of human diseases.” (Heiden-
reich and Zhang, 2016, p. 42) crispr has also aided the derivation of retinal
ganglion cells from human pscs, to model human optic nerves in vitro for re-
search into optic nerve disease (Sluch et al., 2015). The very high efficiency of
these types of methods, coupled with the relative ease and speed of the pro-
cess, and the ability to use and screen many thousands of cell lines in parallel,
means that this type of approach to understanding the basis of human disease
and to identify therapeutic targets and therapies must be the way forward, in
place of creating GM animals (see Bassett, 2017). While the aforementioned
off-target effects are a confounding factor, they matter much less in cell lines
than in animals, because there are no ethical problems; and cell lines can be
produced, screened, and evaluated much more quickly and efficiently.

8 Summary

Acknowledgement of the suffering of GM animals has, at least, led to some
efforts to reduce it, even if these have not, to date, led to overall reductions
in their creation and experimental use. Guidelines for the use and care of
GM animals, for example, are welcome. Working Groups and international
guidelines have been commissioned to this end (Wells et al., 2006) and are at
least intended to reduce the number of GM animals created and improve the
welfare of those who are. These include requiring attempts to establish the
appropriateness of generating any GM animal, both scientifically and with re-
gard to welfare, involving a harm-benefit analysis; and a stipulation that new
animals should not be generated if similar suitable lines already exist, and/
or if an in vitro method could be used instead (Rose et al., 2013). These guide-
lines need to be widely adopted and enforced, but also greater training of staff

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responsible for care, for example, can only make little or no impact on the
welfare of the many millions of GM animals that will end up in laboratories
worldwide. Ultimately, guidelines or not, GM animals suffer greatly, in their
tens of millions each year. Controversially, one developing effort to address
this, already attempted in rats, is to make GM animals who—while still able
to sense pain—are incapable of finding its sensation unpleasant (Shriver,

Yet, the public demands that such pain and suffering is avoided or con-
trolled at all costs for them to accept animal research, GM or not (Aldhous et
al., 1999; Animal Aid, 2003; Clemence and Leaman, 2016; Leaman, Latter and
Clemence, 2014; tns Opinion & Social, 2010). Generally, people are much less
accepting of GM animals than they are of GM plants and GM food compared to
other GM applications. While perceptions of risk are offset by perceived ben-
efits (Frewer et al., 2013), there is evidence that the EU populace has in the past
“morally rejected genetic engineering of animal models of disease,” which is
incompatible with the direction in which worldwide attitudes and laws are
moving (Rollin, 2015, p. 114). Utilitarians may argue that human benefit out-
weighs this pain and suffering. But, given the degree of animal pain and suffer-
ing involved, both qualitatively and quantitatively, the relatively small number
of people who stand to benefit from any breakthrough for many of the rare
genetic diseases that may be modelled, and how unlikely GM animals are to
contribute to breakthroughs given the burgeoning evidence against them, how
can this be so? This is especially true if any harm-benefit analyses applied to
license applications for animal experimentation are conducted properly and
more stringently, as there are calls for authorities to ensure (Würbel, 2017).

Even if one presumes sufficient human benefit from research on GM ani-
mals, which I (and many others) believe is not supported by evidence, there
remain serious scientific issues with, and ethical/welfare consequences of,
genetic engineering. Despite the best currently available method of crispr
having “swept through labs around the world” recently, and being touted as a
“revolution” (Ledford, 2015, pp. 20–21), it is still considered as being “in an im-
mature phase of development” and “not yet ready for therapeutic applications
in humans given the low editing efficiency” (<15%) (D’Agostino and D’Aniello, 2017, p. 4). This is also due to the persistent concerns over the stubborn na- ture of off-target mutations, occurring at frequencies of up to 60%, more than the best efficiency of intended on-target modifications. Even if off-target is- sues can be greatly reduced, which is questionable, they are still of concern clinically, as “Even low-frequency events could potentially be dangerous if they accelerate a cell’s growth and lead to cancer” (Ledford, 2015, p. 22).

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465Genetic Modification of Animals

The efficiency of crispr translation to clinical applications is also of con-
cern. Scientists using crispr to correct a disease-causing mutation in mice in
a gene therapy experiment had to “pump large volumes of liquid into blood
vessels—something that is not generally considered feasible in people” and
this corrected the mutation in just 0.4% of the mice’s cells, not enough to be
effective (Ledford, 2015, p. 21). Delivery methods for introducing the crispr
apparatus to cells also need optimizing (Peng, Lin and Li, 2016). Carrier dna
used to introduce crispr to target cells may become integrated into the host
genome, causing off-target effects, which may disrupt the genome editing pro-
cess and can cause toxicity. Alternative methods may be stressful to cells, alter-
ing gene expression, or leading to high off-target effects (Peng, Lin and Li, 2016).
Despite these concerns, the first clinical trial involving crispr commenced in
October 2016, when knockout immune cells were injected into patients as po-
tential therapy for metastatic non-small cell lung cancer (Cyranoski, 2016a);
and now crispr is already part of ten clinical trials just a few years after it
became mainstream ( It remains to be seen if they will be
successful, and if so, how much they rely on GM animal research.

9 Conclusion

GM animal creation and experimentation takes the lives of tens of millions of
animals each year and involves considerable suffering at every stage. Its sci-
entific value is extremely poor, to the point of it being unnecessary, mislead-
ing and therefore harmful not just to the animals involved, but also to people,
who depend on good science to understand, treat, and cure the diseases that
affect us all. The continued insistence of many who practice and fund GM re-
search that animals must be used is without foundation. Non-human animals
have always been bad models for humans due to species differences, and no
amount of genetic modification can remedy that, even if it were perfect. GM
processes are far from perfect, however. Even the best is extremely inefficient,
and confounded not just by those species differences, but also by off-target
effects of the GM process. These issues are at the root of animal research fail-
ing to be relevant and reliable for humans, of animals being poor models for
disease right across the spectrum, and of the failure of 90%-95% of new drugs
in human trials that were successful in animal tests (Bailey, Thew and Balls,
2013; Bailey, Thew and Balls, 2014; Bailey, Thew and Balls, 2015). Moving away
from animal research, including the use of GM animals, has never been more

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Genetic Modification of Preimplantation Embryos: Toward Adequate Human Research

Author(s): Rebecca Dresser

Source: The Milbank Quarterly , 2004, Vol. 82, No. 1 (2004), pp. 195-214

Published by: Wiley on behalf of Milbank Memorial Fund

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Genetic Modification of Preimplantation
Embryos: Toward Adequate Human
Research Policies


Washington University

Citing advances in transgenic animal research and setbacks in human trials of

somatic cell genetic interventions, some scientists and others want to begin
planning for research involving the genetic modification of human embryos.
Because this form of genetic modification could affect later-born children and

their offspring, the protection of human subjects should be a priority in decisions

about whether to proceed with such research. Yet because of gaps in existing
federal policies, embryo modification proposals might not receive adequate
scientific and ethical scrutiny. This article describes current policy shortcomings

and recommends policy actions designed to ensure that the investigational
genetic modification of embryos meets accepted standards for research on human


James Watson, codiscoverer of the structure of DNA; Daniel
Koshland, former editor in chief of Science; and Leroy Hood, a lead-

ing molecular biologist-participated in a symposium on human genetic

engineering (Stock and Campbell 1998). Citing advances in transgenic
animal research and the disappointing results of human somatic cell
genetic interventions, these scientists joined several other symposium
participants in arguing that the genetic modification of early embryos

offers great promise for advancing human health and welfare (Stock and
Campbell 2000b). Accordingly, they called on researchers, scholars, and

Address correspondence to: Rebecca Dresser, Washington University School
of Law, One Brookings Drive, Box 1120, St. Louis, MO 63130 (e-mail:
dresser@wulaw.wustl .edu).

The Milbank Quarterly, Vol. 82, No. 1, 2004 (pp. 195-214)
@ 2004 Milbank Memorial Fund. Published by Blackwell Publishing.


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196 Rebecca Dresser

policy officials to consider when and how to study this form of human

genetic modification.
Those taking a positive view of preimplantation embryo genetic mod-

ification (PGM) emphasize its possible future benefits. For example, they
say, the approach could enable someone with two copies of the gene for

Huntington’s disease to have a biological child unaffected by the dis-
ease. It also could allow parents to “enhance” their children by promoting

resistance to HIV infection or cancer (Capecchi 2000).
Besides extensive animal and other laboratory studies, human trials

would be required to evaluate whether genetic modifications in embryos
were safe and effective for clinical use. In such trials, embryos created

through in vitro fertilization would be genetically modified and then
transferred to a woman’s uterus for gestation. Thus, the health and welfare

of later-born children would be a major ethical and policy concern.

Studies involving the genetic modification of preimplantation em-
bryos would raise significant human subjects issues requiring extensive

expert and public deliberation. If investigators were to propose a human

PGM study, however, the current oversight system would be ill prepared

to respond. Because of the gaps in the current federal policies protecting

human subjects, PGM studies might not receive adequate scientific and
ethical scrutiny.

In this article, I examine PGM studies in light of U.S. oversight poli-

cies designed to protect human subjects. First, I discuss the relevant
scientific developments and argue that scholarly analyses have not de-

voted enough attention to the human research phase of PGM. Second, I

describe current policies governing research involving human gene trans-

fer, research involving human embryos, and research involving human

subjects. Third, I point to policy omissions and uncertainties that could

contribute to the inadequate oversight of PGM research. I conclude with

recommendations for policy action. My goals are to alert scholars and
policy officials to regulatory deficiencies and to create an opportunity
to remedy the problems before PGM studies are undertaken.

Research Developments

The current research efforts to modify human genes incorporate somatic

cell gene transfer interventions. This form of investigational intervention

is designed to modify somatic (nonreproductive) cells in the subject’s

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Genetic Modification of Preimplantation Embryos 197

body. Researchers conducting somatic cell gene transfer studies try to

deliver properly functioning genes to children and adults, with the most
common techniques using genetically modified viruses. In a successful
intervention, the virus infects the appropriate target cells; the normal

genes are integrated into the cell’s genome; and the normal genes assume
their correct function (Walters and Palmer 1997). Although numerous
studies have been conducted since 1990, the approach has fallen short of

earlier expectations. To date, no somatic cell intervention has produced

sufficient evidence of safety and efficacy to gain approval for clinical use
(FDA 2000).

Somatic cell intervention is distinguished from a second approach,
called germ line genetic intervention, which involves modifying genes in

germ (sperm or egg) cells. Such modifications become part of the genetic

material that may be inherited by the initial subject’s descendants. Most
discussions of germ line modification stress its potential effects on future

generations. On the one hand, if a germ line genetic modification had
adverse effects, the burdens could fall not only on direct subjects but
on their descendants as well. On the other hand, successful germ line
interventions could enable a direct subject’s descendants to avoid genetic

disease, to avoid being a carrier of genetic disease, or to benefit from
mental and physical enhancements (Walters and Palmer 1997).

Because PGM would be performed in the cells of very early embryos,
the modification would be maintained as the cells differentiated and

thus would be present in the germ cells of later-born individuals (Resnik,

Steinkraus, and Langer 1999). The effects on the descendants of geneti-

cally altered individuals are, however, of only secondary interest to PGM

supporters. Instead, they see interventions in the early embryo as the

most efficient way to alter genes in a later-born child. They contend
that genetic alterations at the embryonic stage are more likely to have
the desired functional effects than are somatic cell interventions per-

formed after birth. In response to concerns about adverse effects in later

generations, they suggest that future research will produce methods of
blocking the transmission of germ line alterations to the direct subjects’

offspring (Capecchi 2000).
Although the enthusiasm about PGM rests in part on some promising

results in animal studies involving the genetic modification of embryos,

the current techniques are unacceptable for humans. The existing meth-

ods of producing transgenic animals cause extensive damage to many
embryos and surviving animals. Because most methods produce animals

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198 Rebecca Dresser

with different levels of foreign gene expression, further breeding is re-

quired to produce animals with stable and properly functioning foreign

genes (Frankel and Chapman 2000; Friedmann 2003). The use of artifi-
cial chromosomes, embryonic stem cells, cloning, and other innovations

could improve the outcomes in animals, but these techniques may not be

suitable for human application (Friedmann 2003; Willard 2000). Fur-
thermore, the disappointing results in human somatic cell gene transfer

show that what makes sense in theory may not be successful in prac-
tice. In sum, it is difficult to reconcile the optimism regarding human
PGM with the state of the science. At the same time, the rosy predic-

tions about PGM support the need for an adequate oversight system to

prevent premature human applications.

Inadequate Attention to Human
Research Issues

Scholarly discussions of modifying inheritable genes have focused on the
ethical and policy issues that would ensue if modifications were widely

available. For the most part, those who contend that such modifica-
tions are desirable and inevitable and those who challenge this view
emphasize the technology’s broad ethical and social implications, often
overlooking the ethical issues that would arise earlier in the technol-
ogy’s development. For example, the editors of a recent book asked the

contributors to discuss whether genetic modifications “no more risky
in humans than natural conception” would be acceptable and desirable
(Stock and Campbell 2000a, 97). Another recent discussion analyzed
the major ethical arguments for and against such modifications on the

“optimistic assumption that the methods will gradually be refined until

they reach the point where gene replacement or gene repair is technically

feasible and able to be accomplished in more than 95 % of attempted gene

transfer procedures” (Walters and Palmer 1997, 80).

Although some analysts have voiced concern about the ethics of hu-

man testing, they have not examined the research issues in detail. For

instance, a working group convened by the American Association for
the Advancement of Science (Frankel and Chapman 2000) described the

preclinical research advances that would be necessary before human trials

should be considered. The group did not, however, evaluate inheritable
genetic modifications in light of the federal policies governing human

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Genetic Modification of Preimplantation Embryos 199

subjects research. In the same vein, a recent philosophical analysis ac-
knowledged that human trials of germ line genetic interventions would

present serious risks and uncertainties but nonetheless simply called for

“careful scrutiny of any protocols for experiments involving those inter-
ventions” (Buchanan et al. 2000, 194).

The ethics and policy literature has neglected the human research stage

of technology development. Scholars and other writers have not devoted
enough attention to the human research that would be necessary to
ascertain whether PGM would be an acceptable health intervention. In
turn, policymakers have not devoted enough attention to the oversight

that would be appropriate for PGM research.

Although federal research policies contain rules and guidance rele-
vant to designing acceptable PGM studies, significant policy gaps exist

as well. This inconsistent coverage reflects the limits of federal poli-
cies governing gene transfer research, human embryo research, and the

protection of human research participants. A second set of policy issues

concerns the appropriate interpretation of the current regulations. Re-

view bodies would confront many questions in applying the existing
policy provisions to PGM proposals.

Federal Policies Governing Human
Genetic Research

National Institutes of Health

Some proposals to study PGM in humans would be subject to federal
oversight systems governing gene transfer research. The Recombinant
DNA Advisory Committee (RAC) of the National Institutes of Health
(NIH) reviews proposals to conduct gene transfer research in institu-
tions receiving federal funds for any type of recombinant DNA research.

Privately funded studies need not be reviewed by the RAC, although
officials encourage sponsors to submit such studies for RAC evaluation.
Strictly speaking, the RAC lacks the authority to prevent even feder-

ally funded gene transfer proposals from being implemented. However,

federal officials may require a full RAC review and discussion of pro-
posals raising “important scientific, safety, medical, ethical, or social
issues” (Recombinant DNA Advisory Committee 2002, 7). Because the
review and discussion are open to the public, investigators and sponsors

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200 Rebecca Dresser

disregarding the RAC’s recommendations could face severe criticism.
The RAC’s recommendations are also distributed to NIH officials, who

may invoke their funding authority to induce compliance. Finally, RAC
materials are available to institutional review boards (IRBs), which can

refuse to approve research proposals that disregard the RAC’s recom-
mendations for protecting human subjects (King 2002).
Investigators submitting gene transfer research proposals to the RAC

must respond to a series of questions in the NIH’s Guidelines for Research

Involving Recombinant DNA Molecules (NIH 2002). These questions
seek general information pertinent to human subjects protection, such as

the study intervention’s expected risks and benefits, facts to be disclosed

to prospective participants, and criteria for subject selection. But the
guidelines do not cover other topics relevant to human subjects protec-
tion in PGM studies.

This omission is due in part to the RAC’s current stance on human
studies of germ line modification. The RAC’s official position is that it

“will not at present entertain proposals for germ line alterations” (NIH
2002, 94). But the RAC’s definition of germ line studies would not nec-

essarily encompass PGM research. According to the NIH’s guidelines,
a germ line alteration “involves a specific attempt to introduce genetic

changes into the germ … cells with the aim of changing the set of genes

passed on to the individual’s offspring” (NIH 2002, 94). As noted ear-
lier, supporters today stress PGM’s potential benefits for the children

who are expected to develop from genetically modified embryos. These

researchers see changes in the genes of the direct subjects’ offspring as
an unavoidable side effect of PGM rather than its aim. Thus, the RAC’s

refusal to review germ line studies might not apply to PGM proposals
whose primary objective is to change the genes in direct subjects. At the

same time, the NIH’s current guidelines leave the RAC unprepared to
conduct a thorough review of PGM proposals.

Recent developments could lead the RAC to revise its policies. In the

late 1990s, researchers asked the RAC to consider preliminary protocols

for in utero gene transfer in humans. They argued that genetic alterations

at the fetal stage were needed to mitigate the harm produced by certain
mutations. The RAC, however, determined that its approval would be
premature, due to inadequate preclinical data regarding the risks and po-
tential benefits to the fetuses (and ultimately the children) who would

be the study’s subjects. The RAC also expressed concern about possi-
ble germ line effects, because the genetic modifications would occur

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Genetic Modification of Preimplantation Embryos 201

relatively early in the subjects’ development (Recombinant DNA Advi-
sory Committee 2000). Despite this concern, the RAC has said it would

be willing to consider future proposals for in utero gene transfer research

(NIH 2002). If the RAC does review such proposals, it will have to de-
velop a systematic approach to evaluating potential germ line effects in

this form of genetic modification research.

In 2001, a second event highlighted the need for the RAC to pay closer

attention to potential germ line alterations. At that time, the RAC was

shown evidence that foreign DNA was present in the seminal fluid of
men participating in a somatic cell gene transfer study. Although there

was no indication that the foreign DNA had been incorporated into
the men’s sperm cells, officials acknowledged that certain somatic cell

gene transfer approaches might cause germ line alterations (National
Human Genome Research Institute 2002). This incident put pressure
on the RAC to scrutinize more carefully the potential germ line effects
in somatic cell gene transfer studies.

Guidelines addressing possible germ line effects in in utero and so-
matic cell gene transfer studies could form the foundation for guidelines

addressing such effects in PGM studies. All three forms of research
would require attention to similar matters, such as appropriate long-
term follow-up procedures for direct subjects and their offspring. But

PGM would also raise a distinct set of questions about human subjects.
For example, unlike the other two types of research, PGM studies would

raise questions about the storage, disposition, and control of genetically

modified embryos. Until the RAC completes a focused inquiry into the

protection of PGM subjects, it will not be prepared to review proposals

to modify genes in embryos expected to develop into children.

Food and Drug Administration

The Food and Drug Administration (FDA) operates a second federal
oversight system for human gene transfer studies. The agency requires
that human tests of “products containing genetic material. .. to alter the

biological properties of living cells” conform to the same standards that

govern drug tests (FDA 1984; FDA 1993, 53, 249). Research sponsors
must secure an investigational new drug (IND) exemption before test-
ing genetic material in humans. The IND application must describe the

investigator’s plans for protecting human subjects and include a com-
mitment to submit the study for an IRB evaluation (FDA 2003a). In

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202 Rebecca Dresser

contrast to the RAC, the FDA has the authority to block human tests,

including industry-sponsored proposals.

Like the RAC, the FDA has not explicitly addressed human subjects
protection in germ line modification research. In a guidance statement

for industry sponsors, the FDA presents its standards for human testing

of interventions involving genetically modified cells. But the document

does not cover product tests involving “genetic modification aimed at
the modification of germ cells” (FDA 1998, 3). Again, the exclusion
of germ line modification would not necessarily apply to PGM tests
aimed at modifying the genes of direct subjects. But the FDA’s failure

to consider human subjects protection in PGM means that the agency is

not prepared to evaluate PGM product testing.

Recent developments could generate revisions in the FDA’s policy.
Because of the possible germ line effects produced by somatic cell gene

transfer techniques and by certain interventions aimed at enhancing
women’s fertility, the FDA is considering policies that address germ
line risks in these contexts (FDA 2002). Although this response might
signal the beginning of a policy approach to PGM research, an ex-
panded inquiry would be needed to develop a robust oversight system
for human PGM (Palmer and Cook-Deegan 2003). The policy would
have to address matters unique to PGM, such as the control of genet-
ically modified embryos. For the agency to exercise adequate human
subjects oversight, its policies must be more closely tailored to PGM

U.S. Policies Governing Human
Embryo Research

For the past two decades, policy discussions of human embryo research
have focused on laboratory studies that require the destruction of early
embryos. But when novel interventions, such as genetic modification,
target embryos expected to be transferred for gestation, the interventions
could affect the health and welfare of later-born children. As a result,

the interventions should be evaluated according to regulatory policies
governing research involving human subjects.

Advisory groups have recognized this dimension of embryo research.

In 1979, the Ethics Advisory Board of the U.S. Department of Health,
Education and Welfare issued a report on research involving human

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Genetic Modification of Preimplantation Embryos 203

in vitro fertilization (IVF) and embryo transfer (U.S. DHEW 1979).
Department officials had asked the board to consider whether such re-

search was ethically acceptable and could be eligible for federal fund-
ing. In its report, the board expressed concern about the safety of
IVF and urged researchers and clinicians to collect data that could
shed light on the procedure’s possible risks to children. But human
subjects policies were never established in response to the board’s

In the early 1990s, the NIH’s director asked another group, the
Human Embryo Research Panel, to consider the ethics of embryo re-
search. The panel determined that preimplantation embryos should be
regarded as human research subjects when investigators intend to trans-

fer them to a woman’s uterus. The panel then recommended that research

interventions affecting such embryos be permitted only if “there is rea-

sonable confidence that any child born as a result of the procedures has

not been harmed by them” (NIH 1994, 41). Again, however, the ad-
visory group’s recommendations never became official human subjects

Partly because of the absence of federal oversight, rigorous data on the

safety and efficacy of IVF and related interventions are lacking (Schultz
and Williams 2002; Sutcliffe 2002). At this point, only one federal law
explicitly addresses experimental interventions on embryos expected to

become children. This is the provision that prohibits the NIH from
funding research that involves the destruction of human embryos (U.S.

Congress 1996). The provision also bans NIH funds for research in which

embryos are “knowingly subjected to risk of injury or death greater than

that allowed” by the regulations of the U.S. Department of Health and

Human Services (DHHS) governing research on fetuses in utero (discussed

later). The provision sets a level of acceptable risk for PGM studies but

says nothing about other human subjects issues raised by such studies.
Moreover, the law applies solely to studies seeking the NIH’s support.

At this time, the federal regulations governing research involving
human subjects do not explicitly cover investigational interventions in
human embryos expected to be transferred for further development. The

Federal Policy for the Protection of Human Subjects (also known as
the Common Rule) defines a “human subject” as “a living individual”
(Federal Policy 1991, 28,013). Although the language is sufficiently
general to encompass preimplantation embryos when the intent is to
transfer for gestation, it has not been interpreted in this way. The DHHS

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204 Rebecca Dresser

regulations governing research involving fetuses apply only after embryo

A new group, the DHHS Secretary’s Advisory Committee on Human

Research Protections, could possibly respond to this policy problem. The
committee was directed to “provide advice on the responsible conduct
of research involving human subjects,” including “pregnant women,
embryos, and fetuses” (U.S. DHHS 2002b, 1). It remains to be seen
whether committee members will propose policies for studies involving

interventions in embryos expected to develop into children.

Federal Policies Governing Research
Involving Human Subjects

Federal policies to protect human subjects would apply to PGM stud-
ies after modified embryos were transferred to a woman’s uterus. The
basic federal policy is contained in the Common Rule, which governs
proposals supported by or performed at institutions funded by the NIH
and most other federal agencies. The Common Rule requires investiga-

tors to submit human study proposals to multidisciplinary IRBs, which

determine whether the proposals meet the regulatory demands for a
reasonable balance of risks and anticipated benefits. Institutional re-
view boards also evaluate the research team’s plans for explaining the
study to prospective participants and for ensuring that a study’s poten-
tial burdens and benefits will be equitably distributed (Federal Policy

Studies conducted by employees of institutions receiving funds from

the NIH and other DHHS agencies must also comply with regulations
governing vulnerable populations that would be included in PGM re-
search. These regulations include Subpart B: Additional DHHS Protec-
tions for Pregnant Women, Human Fetuses and Neonates Involved in
Research (U.S. DHHS 2001), and Subpart D: Additional DHHS Protec-
tions for Children Involved as Subjects in Research (U.S. DHHS 2002a).
The regulations require IRBs and investigators to pay special attention
to the complexities of decision making when pregnant women and cou-

ples consider enrolling in studies that will affect an expected or existing
child. The regulations also limit the acceptable research risks to fetuses

and children and give sufficiently mature children a role in deciding
whether to enter or remain in a study.

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Genetic Modification of Prenimplantation Embryos 205

Certain human subjects protections would also apply to PGM stud-
ies in private settings not explicitly covered by the Common Rule. The

Food and Drug Administration’s regulations cover the investigational
uses of new biological products in humans, requiring such proposals
to be reviewed by an IRB applying the Common Rule’s substantive
provisions on acceptable risk-expected benefit ratios, informed decision
making, and subject selection (FDA 2003b). Since 2001, the FDA has
applied the DHHS’s pediatric research rules to privately sponsored re-
search that the agency regulates (FDA 2001), but it has not adopted the

DHHS’s provisions governing research involving pregnant women and

Although the federal regulations governing human subjects research

offer guidance on the appropriate conduct of PGM studies, the guidance
is incomplete. The existing policies offer a framework for protecting
many of the rights and interests of prospective parents participating
in research but leave later-born children vulnerable to harm. Both the

DHHS and the FDA lack policies explicitly addressing situations in
which investigational modifications in the genome of an embryo could

have health consequences for a later-born child. As noted earlier, the fed-

eral embryo research statute limits the permissible risk in such situations,

but it does not address parental decision making and other ethical consid-

erations relevant to this form of investigational intervention. Moreover,
the federal embryo research statute applies solely to NIH-funded studies.

These gaps in federal oversight leave human subjects without adequate

protection in certain settings. Some fertility specialists, particularly those

working in clinics not affiliated with academic medical centers, are
unaccustomed to submitting study proposals for FDA and IRB review
(Frankel and Chapman 2001). In 2001, for example, infertility specialists

published the results of a study using a technique called ooplasm transfer,

which produces embryos with a mixture of mitochondrial DNA from
two women (Parens and Juengst 2001). The infertility researchers had

not obtained an investigational new drug (IND) exemption for this work.
After the results were published, FDA officials notified researchers that

an IND exemption would be required. But this was four years after
the first pregnancy involving an ooplasm transfer. Meanwhile, FDA
officials expressed concern about the procedure’s safety (FDA 2002). To
prevent similar unauthorized investigations, clear human subjects rules

are needed governing novel interventions in embryos expected to be
transferred for gestation.

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206 Rebecca Dresser

Uncertainties in Interpreting Current
Human Research Rules

The existing human subjects policies cover investigational interventions
involving adults, children, and fetuses in utero. Researchers and review-

ers, however, would encounter numerous questions when applying the

Common Rule and DHHS requirements to PGM studies. The following
is a survey of the major issues that they would encounter.

The Common Rule

The Common Rule establishes three basic requirements for human stud-
ies. First, the risks to the subjects must be minimized, and any remaining

risks must be “reasonable in relation to anticipated benefits, if any, to
subjects, and the importance of the knowledge that may reasonably be

expected to result” (Federal Policy 1991, 28,015). For PGM studies, the
reasonableness of risks to the subjects depends largely on the seriousness
of the target condition, the available alternatives to PGM, and the social

value of the anticipated research data.

Whether PGM studies present reasonable risks could be a point of
contention. Studies aimed at avoiding genetic diseases in children could
provoke disagreement because of the available alternatives to PGM. In
most cases, for instance, preimplantation genetic diagnosis (PGD) of-
fers prospective parents a better chance of having a healthy child. In
this technique, early embryos are genetically tested, and those testing
positive for disease are not transferred for gestation (Botkin 1998). The

PGD technique raises ethical concerns because it results in discarding
embryos. But because PGM also would result in discarding embryos
(experts expect that some embryos would be damaged or the mutations
would not be corrected), it would not be a morally preferable alternative
to PGD. The PGD alternative is not available in the relatively rare case
in which both members of a couple have two copies of recessive disease
genes or one member has two copies of a dominant disease gene. Yet even

these couples have other reproductive options, such as adoption or the
use of donor gametes. Because PGD and other alternatives present fewer
risks to later-born children, reviewers could find that PGM studies pre-

sented unreasonable risks to subjects. It could also be difficult to enroll

enough subjects in a PGM study to produce generalizable knowledge,
which would reduce the study’s value to society.

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Genetic Modification of Preimplantation Embryos 207

Studies to improve normal characteristics would present an additional

source of controversy. Some members of society may see the benefits of ge-

netic interventions for enhancement as sufficiently important to justify

the risks. As Buchanan and his colleagues observed, “If individuals-or
groups of individuals-value some enhancements very highly, they may

well be willing to take significant risks to produce it . . in their chil-
dren” (2000, 195). The question is whether the Common Rule’s demand
for reasonable research risks permits studies exposing to harm embryos

expected to develop into healthy children in exchange for the uncertain

possibility of physical or mental enhancement.

Investigators and review groups must also develop a principled ap-
proach to evaluating PGM’s potential consequences to future genera-
tions. In some medical and research contexts, individuals are exposed
to radiation, chemotherapy, and other interventions that may cause mu-
tations in germ line cells (Blaese 2003). In these situations, the bene-
fits to the recipients are regarded as sufficiently valuable and probable

to justify potential harms to their offspring. In the context of PGM
research, however, the potential benefits to direct subjects would not
be as clear. Evaluating PGM’s possible consequences to descendants
would be further complicated by the need to rely initially on nonhuman

and other preclinical data. Review groups would also have to consider
the possibility that future techniques could prevent the transmission
of germ line changes or reduce adverse effects in descendants (Resnik

Fulfilling the Common Rule’s second basic directive could be chal-
lenging, too. This directive requires investigators to help prospective
participants or their representatives make informed and voluntary deci-

sions about enrolling and remaining in research. The duration of PGM
studies would introduce a special complexity. Because genetic alterations
could affect the subjects later in life, as well as their offspring, many years

of data collection would presumably be necessary. Thus, research discus-
sions would begin with the prospective parents considering PGM and
would occur later with the parents of the genetically modified children.
Eventually, investigators would have to discuss the research with child
subjects mature enough to understand basic study information. When
these children turned eighteen, they would be free to decide whether
to participate in the research. Those subjects who bore children would
also be responsible for deciding whether to allow their offspring to be
followed. Research teams would have to ensure that prospective subjects

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2 08 Rebecca Dresser

in each of these groups were given an opportunity to choose both to
begin and to continue participating in the study.

The Common Rule’s third major requirement mandates equitable sub-

ject selection. This provision is designed to ensure that the harms and
benefits of the research are fairly distributed among groups and indi-

viduals. Although pregnant women would participate in PGM studies,
the subjects at greatest risk would be their later-born children. In the

early phase of PGM studies, a vulnerable population would be exposed to

relatively high risk, primarily to advance knowledge that could benefit
others. Review groups would have to decide whether PGM’s potential
benefits justified exposing vulnerable subjects to this level of risk.

DHHS Policies Governing Research Involving
Vulnerable Populations

The DHHS provisions governing research involving vulnerable popula-
tions would raise more questions for groups considering PGM proposals.

These provisions, and the ethical principles they incorporate, would raise

serious questions about the acceptability of initial human studies. Ini-
tial human tests of drugs and biological products are designed mainly to

obtain information about dosage and toxicity. Such studies also seek, “if

possible, to gain early evidence on effectiveness” (FDA 2003c, 62). A cru-
cial regulatory issue would be whether the reviewers classified the initial

PGM studies as offering a potential benefit to later-born child subjects.
Their decision would turn on whether the data from animal and other

preclinical investigations furnished a reasonable basis for predicting a
direct benefit to child subjects.

The DHHS’s regulations restrict the level of permissible risk when
study interventions do not offer subjects the prospect of a direct benefit.

In this situation, Subpart B permits only minimal risk to fetuses (U.S.
DHHS 2001). According to the Common Rule, minimal risk “means
that the probability and magnitude of harm or discomfort anticipated
in the research are not greater in and of themselves than those ordinarily

encountered in daily life or during the performance of routine physical
or psychological examinations or tests” (Federal Policy 1991, 28,013-4).

Although federal regulations do not include a specific definition of
minimal risk to fetuses, the National Commission for the Protection of

Human Subjects of Biomedical and Behavioral Research considered this
matter extensively (1974). The commission members concluded that

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Genetic Modification of Preimplantation Embryos 209

minimal research risks are those that are similar to the risks of normal

fetal development and routine obstetric tests. They also concluded that

the pregnant woman’s ability to terminate her pregnancy should not
affect the level of fetal risk permitted in research. Congress incorporated

this latter conclusion into the law governing federally funded research

involving fetuses (U.S. Congress 2003).
In a similar approach, Subpart D limits the risks to children from

research interventions that do not offer a direct benefit. Institutional

review boards may approve a study intervention offering child subjects
no direct benefit if the intervention presents no more than minimal
risk. Alternatively, such interventions may be approved if they present

“a minor increase over minimal risk,” involve “experiences to subjects
that are reasonably commensurate with those inherent in their actual or

expected medical… situations,” and are “likely to yield generalizable
knowledge about the subjects’ disorder or condition which is of vital
importance” (U.S. DHHS 2002a, 121).

It is unclear whether initial human PGM studies could be approved
under the regulations governing research interventions that present no

prospect of direct benefit. To support their approval, compelling animal
and other preclinical data demonstrating the probable safety for humans
would be necessary. A related issue is whether the concepts of “mini-
mal risk” and “minor increase over minimal risk” should be evaluated

against the usual risks faced by healthy children or by children with
the genetic condition being studied. The latter approach could permit
certain higher-risk research procedures to be classified as minimal risk,

because the usual risks faced by children with serious genetic diseases
are much higher than those faced by healthy children (Kopelman 2000).

Different issues would be raised if the initial PGM studies were clas-

sified as offering fetuses and children the prospect of a direct benefit.

The federal regulations permit fetuses and children to be exposed to
research interventions presenting greater than minimal risk if the inter-

ventions also offer them the prospect of a direct benefit. The pediatric

research regulations deem as acceptable those interventions offering a
direct benefit if the “relation of the anticipated benefit to the risk is at

least as favorable to the subjects as that presented by available alternative

approaches” (U.S. DHHS 2002a, 121). Investigators seeking to perform
PGM to avoid genetic disease thus would have to show that existing
therapies offered a similar or less satisfactory balance of risks and poten-

tial benefits. Investigators proposing PGM to produce disease resistance

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2 I0 Rebecca Dresser

or other enhancements would need to establish that the possible benefits

were significant enough to justify the risks to healthy children, taking

into account the available alternatives to achieving such enhancements.

It is possible that federal officials would permit PGM studies that do

not conform to these DHHS requirements. The regulations governing
research involving pregnant women and fetuses establish a national re-

view process for permitting research not otherwise approvable. In this
process, the local IRB, the DHHS secretary, and a national panel of
experts must determine that the research offers “a reasonable opportu-

nity to further the understanding, prevention, or alleviation of a serious

problem affecting the health or welfare of pregnant women [or] fetuses.”

The secretary and national panel must also conclude (following a public

meeting and an opportunity for public comment) that the study will be

consistent with “sound ethical principles” and satisfy the usual require-
ments for informed choice (U.S. DHHS 2001, 56,780). The pediatric
research regulations establish a similar process (U.S. DHHS 2002a). Al-
though the requirements for a national review would ensure that such

proposals received public scrutiny, the policies’ substantive standards are

sufficiently vague that PGM interventions might qualify for approval

through this process.


This examination shows that U.S. policies offer limited protection to
human subjects in research involving the genetic modification of em-
bryos expected to develop into children. The inadequacies of current
policies mean that officials are not fully prepared to respond to future

proposals for human PGM research and to the harmful consequences of

any objectionable PGM experiments that might be performed. Certain
policy shortcomings are relevant not only to PGM research but also to

cloning and other investigational interventions affecting preimplanta-
tion embryos expected to be transferred for gestation (Dresser 2003).

Three policy actions would go a long way to remedying this situa-
tion. First, the RAC or another qualified interdisciplinary body should

begin work on a human subjects policy specifically for PGM studies.
Officials from both the NIH and the FDA should help to formulate the

policy. Second, federal agencies should develop a human subjects policy
to protect later-born children who might be affected by PGM and other

investigational interventions in preimplantation embryos. Third, the

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Genetic Modification of Preimnplantation Embryos 2 II

FDA should apply the DHHS’s regulations protecting pregnant women
and fetuses to privately funded studies of the products it regulates.

In addition, scholars and other analysts should respond to the policies’

inadequacies. Experts in relevant fields should develop ethically defen-

sible policies to guide PGM and related studies, and they should also
develop defensible applications of existing policy provisions to PGM re-
search. Without such efforts, the nation will remain unready to protect

human subjects in this emerging research area.


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Acknowledgments: My research was supported by the National Human Genome
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  • Contents
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  • Issue Table of Contents
  • The Milbank Quarterly, Vol. 82, No. 1 (2004), pp. i-vi+1-222
    Front Matter [pp. i-100]
    In This Issue [pp. 1-4]
    Is Income Inequality a Determinant of Population Health? Part 1. A Systematic Review [pp. 5-99]
    Social Determinants and Their Unequal Distribution: Clarifying Policy Understandings [pp. 101-124]
    Addressing the “Risk Environment” for Injection Drug Users: The Mysterious Case of the Missing Cop [pp. 125-156]
    Changes in Elderly Disability Rates and the Implications for Health Care Utilization and Cost [pp. 157-194]
    Genetic Modification of Preimplantation Embryos: Toward Adequate Human Research Policies [pp. 195-214]
    Back Matter [pp. 215-222]

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