A new cautionary tale for heritable genome editing

A fundamental concern about applying gene editing to human embryos is how to limit the risk of errors, or “off-target” effects.  One makes an edit to change a bad gene’s defect, and presumably prevent the disease the defective gene would cause.  But the current methods to do that, although apparently highly selective, might still make other, unwanted changes as well—with possible deleterious, even disastrous, consequences.

Heretofore, the attention to these “off-target” effects has largely been directed to changes in genes that are separated from the target gene.  However, a recent news item in Nature describes three recent experiments with human embryos in the laboratory, in which large defects were induced in the chromosomes bearing the target gene—that is, right next door.  The difference is a bit like the difference between damage by shrapnel (distant effect) and blowing a 6-foot hole instead of a pinhole (near effect).  The latter is now the new concern.  Apparently, and, for one who does not live the scientific details daily, amazingly, prior analytic techniques were missing the possibility of these big, close-in errors.  “CRISPR gene editing in human embryos wreaks chromosomal mayhem,” the headline reads.  Geez Louise…

The technical details are still to be worked out, but one possibility is that, after the targeted gene is cut by the editing mechanism, the way that repair of the genes is done by the human embryo creates the possibility of introducing errors by copying or shuffling of a big chunk of the gene.  These processes are not fully understood in human embryos, and may be different from what pertains in mouse or other animal embryos, or in single human cells such as egg cells or newly-fertilized eggs.

The big technical message is that a lot is poorly understood and will take a ton of work to sort out before one can be confident that a pregnancy carrying a gene-edited to-be-born human will birth a healthy baby, in the immediate outcome, never mind consequences later in life.  It further suggests that no amount of animal work may lay the matter to rest.  From that it’s hard to avoid the conclusion that many embryos will need to be created, altered, and destroyed for research purposes if heritable human genome editing is to proceed with some assurance of safety.  How long would those embryos have to be kept alive to test?  Quite possibly longer than the few days currently possible and accepted by the scientific community.

Absent that, trying to birth gene-edited children would mean, as this blog said some time ago, that “the babies are the experiment.” 

And, even if one does not grant moral status to the human embryo from the point of conception, one is compelled to seek an accounting of the compelling unmet medical need that supports a careful benefit-risk analysis.  Risks to human subjects—embryos, fetuses, eventually-born babies, women donating eggs, perhaps even women carrying partial pregnancies (to allow study of results from a later point in utero?)—seem substantial, overall costs of the effort raise questions of spending the money better elsewhere in the overall health care of society, and alternative approaches to the diseases in question must all be considered.

Geez Louise.

One other point: the Nature article cites preprints posted, prior to peer review of the science, on the website bioRxiv.  Operated by the outstanding Cold Spring Harbor Laboratory, the website offers authors the chance “to make their findings immediately available to the scientific community and receive feedback on draft manuscripts before they are submitted to journals.”  Open access and public feed back are good, but the general press often picks up these preprints, whose quality may not have been fully vetted, and runs with headlines—kind of like I am doing here, following Nature.  So we must watch this space to be sure that the research is being accurately described and interpreted.  For the moment, the topic of this post can be taken as another example of “something to watch out for.”

A principalist argument against heritable genome editing

In May of 2019 The New Bioethics carried a paper (purchase or subscription required) by Jennifer Gumer of Columbia and Loyola Marymount Universities, summarizing an argument against heritable genome editing (the kind in which an embryo’s genes are edited so that the change will be passed down to the subject’s descendants), based on Belmont principalism.  A brief outline of the argument:

  • Uncertainties about the safety of the procedure make it highly unlikely at best that the principle of nonmaleficence (“first, do no harm”) will be satisfied.  Even if the technique substantially eliminates unintended, “off target” gene changes or mosaicism (some cells have the change, others do not), uncertainty will remain about whether interactions between genes may be altered, potentially beneficial positive effects of the “bad” genes may be lost, or the edited gene may have different effects in different environments.  Further, the edited gene will persist in the human population. 
    • At least, this concern would appear greatly to limit the number of genetic conditions that would be appropriate for heritable editing, to a few where a very discreet genetic abnormality that causes a devastating disease is well understood.  Such limits would almost certainly be unenforceable, as efforts to edit genes that clearly cause disease would be expanded to edit genes that predispose to or increase risks of disease, or event to insert or add genes thought to protect from disease.  The additional complexity of the tasks would further confound attempts to calculate risks.
  • The justice of heritable genome editing could well be limited by:
    • The costs, either in the individual case or more broadly on the health care system because in vitro fertilization would almost certainly be required to carry out the heritable editing;
    • Diversion of resources from dealing with environmental or socioeconomic conditions with greater overall impact on the health of the human population;
    • A bias against people with disabilities may be fostered.
  • If heritable gene editing included efforts to enhance traits perceived desirable, harms could arise from miscalculations about whether such enhancement truly yields a better life (e.g., if one could be genetically altered to require less sleep), or pressures on the offspring to perform up to enhanced expectations, again violating the principle of nonmaleficence.
  • Efforts at enhancement would create eugenic pressure to extend the enhancement widely through the population, and/or create a split-class society of (presumably wealthy) genetically enhanced “haves” and unenhanced “have nots,” violating the principle of justice.
  • Limiting heritable genetic editing to the few cases of single-gene-caused serious diseases would benefit only a few affected individuals and their parents, by helping the latter to have genetically-related, unaffected offspring, while risks such as those outlined above could affect many, either by creating direct risks in the population or indirect risks of lost opportunities from deferral of attention to other health and societal problems.
  • Likewise, an appeal to autonomy fails.  Procreative freedom has not yet been held to include a right to bear a genetically-related child, much less one free of undesired traits, and even if such a right were recognized, it would not be unbounded, but would be subject to limits set by concerns such as well-being of the resulting child and societal concerns.  Moreover, parental exercise of autonomy for heritable gene editing would limit the autonomy of society by potentially exposing others to unintended risks without their consent, and would limit the autonomy of gene-edited descendants, whose genomes would be determined at least in part by the decisions of their ancestors.

Thus, in brief, runs the argument.  Like the utilitarian argument summarized in my February 6 post, these contemporary discussions are important to review from time to time.  Further perspectives and analysis to follow in future posts.

Controlling gene editing

The title does not mean societal or legal control of gene editing technology.  Rather, it speaks of controlling, or shutting off, a specific gene editing process.  In retrospect, it had to be the case that there is a resistance, or control, mechanism for the CRISPR system, the gene-editing machinery that functions as a way for bacteria to resist invasion by viruses.  An engaging essay in Nature this week discusses this on a level accessible to one who, like me, is not a technical specialist in the field.  Briefly, a few years ago a grad student at UC/San Francisco discovered cases in which the CRISPR system was ineffective in certain bacteria.  Following up led to the discovery of some 50 proteins that can act as “kill switches” for CRISPR.

On a surface level, the implications are clear—learn how to deploy these proteins and one can monitor one’s gene editing efforts for unwanted effects, or for spinning out of control, and if things haven’t gotten too far out of hand, one could turn things off—have an antidote, as it were.

Suppose at some future date that someone were being treated with a gene editing approach for a genetic disease, and things start happening suggesting that other genes than were intended to be the target were being altered.  Presumably one could intervene to treat or prevent the consequences.  Or suppose that genes were being edited to control a certain pest, like malaria-causing mosquitoes.  Presumably there could be an intervention to try to stop the process.

That’s a pretty superficial discussion, but technical experts in the field are trying to learn how to use these “kill switches” to control their gene-editing efforts. 

The also-superficial implication seems clear: these efforts should be understood, and applied in laboratory systems, then perhaps in “somatic” gene editing (treating an existing person for a genetic disease) BEFORE attempts are made to edit human embryos, whether the embryos are intended for gestation or birth or not.  Until things are MUCH more fully understood, there should be no direct work on heritable genome editing.

Chastening and enthusiasm about genome editing

A writer in Nature says that China sent a “strong signal” by punishing He Jiankui and two colleagues with fines, jail times, and bans against working again in human reproductive technology or applying for research funding.  (They lost their jobs as well and may not be able to do research work, presumably in any field, in a Chinese institution again.)  It is encouraging, this writer says, that China took this action demonstrating a commitment to human research ethics.  He and other researchers doing gene-editing work that is not ethically objectionable worry that there may be collateral damage, so to speak, against ANY gene-editing research in China.

Another writer in Nature says cites progress under “appropriate caution” for using gene editing techniques for so-called “somatic” gene editing; that is, editing disease genes in an existing person with that disease, to treat it.  This is, in essence, a form of gene therapy and is ethically permissible under proper research ethical guidelines.  Some clinical trials in progress involve injecting the gene-editing apparatus into a person, while most such trials remove the person’s blood cells, edit them in the laboratory, then re-introduce them into the bloodstream, after which the edited cells are left to mature normally.  The latter approach is particularly attractive to treat genetic blood diseases such as sickle cell anemia.

Both perspectives seem correct, as far as they go—never mind whether Dr. He’s jail sentence fits the crime, as Joy Riley asked on this blog last weekend.  Never mind also whether Dr. He’s research should be published; as Mark McQuain commented, it’s a bit incongruous to want to assess the technical merits of work that should not have been done in the first place.  He linked an opinion in Technology Review that argued, briefly, that because the ethics of editing genes in human embryos is under societal debate, people trying to decide on the ethical merits should be able to assess for themselves whether Dr. He succeeded, technically at what he set out to do.  (The consensus to date seems to be, no, he did not.)   But the role of technical success in assessing the ethical merits of a medical intervention—or, better, an intervention made in the name of medicine—depends on the degree to which the ethical judgment is a matter of making a reasonably reliable of risk and benefit, and the degree to which risk-benefit is a criterion for judging the ethical merits.  And therein, as they say, lies the rub—which I hope to revisit in coming posts.

Can we hop the gene-editing train?

As Joy Riley pointed out on this blog on December 7, the world and the scientific community recently marked, with almost no fanfare, the one-year birthday of “Lulu” and “Nana,” the first (we think) and still only (we think) humans to have had their genes edited heritably—in a way that will be passed on to future generations.  Joy commented these children are “experimental subjects for life,” or, to use the phrase I found and discussed some time ago on this blog, “the babies are the experiment.”  To wit: it is not possible fully to assess and limit the risks of heritable genome editing before actually editing humans.  One must forge ahead.  Even if one were to edit a series of embryos, and abort them at different times during gestation to get a full assessment of their prenatal development, the questions about lifelong effects and effects on future generations would persist. 

And, as mentioned in other posts on this blog earlier this year, there is the issue of “nonphysical” harms to how we understand ourselves and our human existence.

A number of world scientific bodies are assessing, independently of each other, what regulatory safeguards should be instituted, on the assumption that heritable genome editing is something that should be pursued.  Last month, the journal Nature editorialized that efforts by the World Health Organization, US and UK scientific bodies, and a third international commission should not proceed separately (they are all due to report their findings in 2020), but should work together.  The editors apparently think that it would be straightforward, obvious, and right to adopt a moratorium on clinical applications of heritable genome editing, establish an enforced registry for all experimentation in this area, and expand the conversations to include representatives of people with disabilities.  If I read that correctly, it’s hard to disagree.

In the laboratory, things are moving fast and it is well-nigh impossible to keep up with the science or the conversations about it without that work being one’s main occupation.  A recent contribution linked by the Nature editors is called “prime editing” that appears to increase substantially the efficiency of gene editing, raising the prospect of correcting abnormalities associated with the vast majority of genetic diseases.  The relatively naïve, like your present correspondent, might wonder whether this approach could be limited to already-born people with genetic diseases, as treatment, rather than engineer the genomes of the unborn in an apparent attempt to eliminate these abnormalities from the human prospect.

Even thinking about the general public trying to influence where this work leads feels like assuming the role of an old-style hobo, trying to hitch a free ride by jumping onto a moving freight train.  One is liable to fall under the wheels.  But in the case of heritable genome editing, you’re likely to get run over anyway.

“Why did you make me this way?!”

Recently, Jon Holmlund brought us up to date on an effort in Russia to proceed with CRISPR gene editing aimed at eliminating deafness. Coincidently, a recent MedPage article was posted regarding the ethics of using pre-implantation genetic diagnosis and IVF to purposefully select FOR an embryo with genetic deafness for a couple, both of whom were deaf. Both links discuss some of the ethical problems with using medical reproductive and genetic technology for these purposes. While we presently lack the ability to use polygene scoring to accurately “produce” the babies we want, I want to use the remainder of today’s blog to consider what obligations, if any, a genetic engineer (or parents that use their skills) may have toward future children designed using these growing array of genetic technologies.

Deafness seems to me to be rather curious in that it is considered either a serious disability or a desirable trait, depending upon your cultural worldview. No one in any culture would purposefully select for cystic fibrosis or Tay-Sachs diseases for their child. In fact, most want to use medical reproductive and genetic technologies to eliminate these diseases. On the other end of the genetic trait spectrum, some parents want to use these same technologies to purposefully select for more trivial traits for their children – hair and eye color, for instance. Given the triviality of these traits, I hear no one mounting an effort to genetically eliminate any particular hair and eye color. Perhaps I am living a sheltered life?

Nonetheless, with regard to deafness, prior to the promises of our new reproductive technologies, if you were born deaf and did not like it, you could only shake your fist at God or Nature. Now (or very soon), you can shake your fist directly at another human, such as your regional genetic engineer (or your parents who purposefully used her technological skills) and demand a direct answer as to why they purposefully made (or did not make) you deaf. Maybe this angst will be more widespread for the many more trivial traits such as eye or hair color rather than something more significant like deafness?

Building a child is about to become much harder for parents as they become directly responsible for both interior (genetic illnesses) and exterior (hair and eye color) design issues.

“Why DID you make me this way?!”

“Why did YOU make me this way?!”

I wonder how many genetic designers (or the parents that will ultimately bear the direct responsibility for having used the technology) really want that type of responsibility?

Is there already fine print in PGD-IVF contracts holding the doctors/scientists/geneticists harmless for the choices the parents make?

I can’t wait for the late night TV commercials: “Were you born with brown eyes and feel emotionally scarred because you have always wanted blue? Call our law offices as you may be entitled to financial compensation …”

Skepticism about polygene scores to select for IQ and height

One caution when objecting to the prospect of heritable human gene editing is to take care not to overestimate what it technically possible.  That is, an all-too-easy argument is that attempts to edit a disease gene will lead, by momentum if nothing else, to “designer babies,” with children not just being genetically selected but in fact engineered in great detail for traits like attractiveness, athletic prowess, height, and intelligence.  This contributor to this blog has repeatedly taken the position that heritable human gene editing is a project that fundamentally alters the way we see ourselves and each other; that divides the human race into “actors” and “acted upons;” that has no prospect of prospectively assessing long-term, unintended consequences, to an individual subject, subsequent generations, or society at large; and that fortifies a perspective of admitting to the human race only those members we want to admit.

Along the way, we must keep in mind that “designer babies” are not likely to be feasible in the foreseeable future.  One recently-reported case in point is a study by scientists at the Hebrew University of Jerusalem.  A preprint (in advance of publication in a peer-reviewed journal, it is said) is publicly available here.  I daresay the details will be inaccessible to all but specialists in genetics, but a summary of key points is provided by a technical writer at a website called GenomeWeb.  In brief, some of those points:

  • A score based on assessment of multiple genes has previously been suggested to explain only about 5% of the difference between individuals in IQ (300,000 people genetically tested) or 25% in height (700,000 people tested).
  • These researchers tested about 1000 people, and considered about 15,000 genetic variations.
  • They looked at offspring of actual couples and also “simulated” matches for about 500 would-be couples made from individuals for whom they had genomic data.
  • Of note, they appear to have looked at “SNPs,” or “single nucleotide polymorphisms,” which are relatively easy to catalog across the 30,000 or so human genes, and which themselves run into the hundreds of thousands across those genes, but SNPs are far from the whole genetic story.  Larger differences in genes, or how those genes are translated into biological traits, is much more complex to assess.
  • They surmised that, if their score were used to try to predict height, the average gain would be about 2.5 cm (about one inch), with a range of 1-6 cm.  If used to predict IQ, the average gain would be about 2.5 points, with a range of 1-7 points.
  • Then they also looked at 28 actual families with lots of kids, from 3 to 20 (!).
  • For the actual families, the score predicted to cause the tallest child did so for only 7 of the 28 families, and the highest scoring child was actually shorter than average in the family in 5 of the 28 families.  No attempt to assess IQ for these real families, apparently.
  • They point out other reasons why trying to select for IQ might be problematic—potential association with autism and anorexia, for example, as well as just general complexity.
  • They suggest that for most people undergoing IVF, and creating fewer than 10 embryos in the process with less than 100% success after implantation in the womb, the odds are not good for making a reliable forecast of an offspring’s height or IQ.
  • They make these points without commenting more broadly on the ethics or policy wisdom of allowing or encouraging heritable genome editing to proceed.

A complex story, and a developing one, to be sure, but one should not be too quick to accept grandiose promises for predicting complex traits based on genetics.  At least for now, those appear to be rather “ahead of the puck,” shall we say.

Future new CRISPR baby in Russia?

Nature reports that Russian scientist Denis Rebrikov has started experiments intended to lead to editing a gene, in human oocytes (egg cells) associated with human deafness.  Prior reports had claimed that he was working on eggs from deaf women in an attempt to repair the defect and, presumably, provide a normal egg for IVF.  This apparently is not the case—yet.  At the moment, he is using eggs donated by women who can hear, to do experiments on editing the gene in question and ferret out what might go wrong in the process—that is, is the right gene edited, is only the right gene edited, and related questions.   

He says he has had discussions with deaf women, but has not yet sought approval from the Russian regulators to try IVF with a gene-edited egg.  The regulators appear reluctant, and Rebrikov says he will not proceed without prior approval.  He had previously said he wants to edit the same HIV-susceptibility gene that was edited in twin babies born in China last year, but it looks like there aren’t too many candidates for that approaching him, and that attempt has not gone forward—yet.

He’s clearly impatient.  Other scientists working in the gene editing field—which has broad applications short of making “gene-edited babies”—are urging patience, and saying that it is at a minimum rashly irresponsible to rush ahead with the effort, particularly for non-fatal conditions like deafness.  And they are right—too little is known to justify the effort—yet—even if one thinks there are conditions for which it ethically could or even should be attempted.

But “the field” is working hard to define a path forward.  The second meeting of an international panel discussing how to move ahead meets in London November 14-15.

Nature includes a brief Q+A with Dr. Rebrikov.  Forgive me, but some of it is chilling, reflecting blindness to the deeper issues.  Paraphrasing selected questions, quoting the answers, offering italicized commentary:

  • Question:  don’t the risks of trying this outweigh the benefits, for a non-life-threatening condition like deafness?  Answer: “Any new drug carries certain risks. The deafness model is the most appropriate for applying genomic editing at the zygote [newly fertilized egg] stage. And it is only for deaf parents to decide whether … deafness is enough to not expect the same for their child.”  Beg pardon:  heritable gene editing is NOT A DRUG, and the risk-benefit decision is NOT solely the province of private decisions about reproductive-related risks.
  • Question:  the regulators point out that editing people is currently not permitted.  Answer: “Laws are written to change them. As soon as we demonstrate the safety of technology, the rule will change.”  Ahem: some laws are enduring, even eternal—cf. divine law. Recognizing that the regulators’ judgment is not divine, eternal law, reverent attention to the latter should be a paramount concern.  And ‘safety’ appears to be narrowly defined here, blissfully ignoring the deeper human questions posed by modifying people’s genes permanently.
  • Question: people trying to build a regulatory framework for human genome editing think researchers should slow down until the framework is agreed upon. What do you say?  Answer: “Are you serious? Where did you see the researcher willing to slow down?”  Hello!  McFly!  We are not ASKING you to slow down.
  • Question: Russian regulators and the World Health Organization say it is too soon to create edited children.  What do you say?  Answer:  “What does it mean, too soon? Lenin said ‘yesterday was too early, tomorrow it will be too late.”.

Lenin?? LENIN?!  For real??

Addressing gene editing with “thin” bioethics

Yesterday’s post on this blog, by Steve Phillips, warned that a narrow, “rules limited” approach to bioethics reduces ethics in science and medicine to matters of regulatory compliance and risks making thoroughly logical conclusions based on faulty premises that are adopted without regarding “deeper ethical thinking” for which scientists’ thinking must be brought under the discipline of broader humanitarian reflection if correct basic notions of what it is to be human, and what humans should be up to, are to be arrived at.

A different but closely related way to look at this was suggested by John Evans of the University of California, San Diego in his contribution to Human Flourishing in an Age of Gene Editing, a new collection of essays, edited by Erik Parens and Josephine Johnson.  In brief, Prof. Evans commented that too much of bioethics is “thin,” reduced to the Belmont principalism (respect for persons/autonomy; beneficence/nonmalificence; justice) governs human subject research.  This “thin” bioethics is convenient for regulators to use to derive a manageable set of rules, and for scientists to, if you will, hide behind (my expression, not Prof. Evans’s).  Rather, he writes, we must be willing to criticize the assumption that all we need to ask about technology is how to use it, and seek a deeper wisdom about what is a good or worthy human life, for individuals or communities.  In making this argument, he appeals to “critics of technology,” both politically conservative (Leon Kass) and politically liberal (Jacques Ellul).  Jacques Ellul!  How often does anyone hear him mentioned anymore?  How many of us have read him?  (I venture fewer than should!) 

This criticism of worshipping at the Belmont altar, if you will, is hardly new, but it’s critical, especially when something as profound as heritable human gene editing is being considered.  You see, Belmont principalism is quite robust when asking how to deal with clinical trials.  But it really most closely applies to things like regulated drug development, and germline gene editing goes far beyond drug development.  It isn’t drug development at all, and cramming it into the conceptual framework of drug development is fundamentally misguided.

Nonetheless, the International Commission on the Clinical Use of Human Germline Genome Editing appears to be proceeding merrily along the drug development path. The second meeting, in London, is next month; one can sign up for a webcast. Just check out the agenda, especially day 2’s planned sessions on risk-benefit analysis and defining “a translational pathway.”  That language applies to new therapy development, not fundamental alterations of human inheritance.

One should keep in mind also that the assumption one can assess risks and benefits is only as good as one’s data.  This week it is reported that scientists have retracted an analysis suggesting that babies edited for an HIV-susceptibility gene might be at risk of relatively short life spans, something this blog poster readily jumped on in his June 6, 2019 post.   But, then again, so did the prestigious journal Nature Medicine, so I guess I shouldn’t beat myself up too much.  Seems the researchers didn’t define matters carefully enough.  Even if this particular analysis, from a large database of human genetic data, was flawed, similar analyses in the future might be helpful, it is argued.  Until more is known, it is further argued, one should not seize on a retracted analysis to infer a full “green light” to edit unborn babies’ genes.  But that may take “thicker” bioethics than whatever risk-benefit analysis we think we can muster now.

Fewer U.S. Twins and the Development of IVF

Readers of this blog may have seen the report in the general press that, after three decades of increases, the rate of twin births in the U.S. has declined by 4% from 2014 to 2018.

Those three decades correspond to the era of IVF, since the birth of Louise Brown in England in 1978.  It seems likely that changes in IVF practice contributes at least in part, if not substantially, to the trend in twin births.

Specifically, doctors at IVF clinics are more commonly implanting only one, rather than more than one, embryo back into a prospective mother’s womb with each attempt at a live birth.  Multiple pregnancies—even twins, not just “Octomom” scenarios—carry increased risk for mother and babies.  Previously, two or more embryos were implanted in an effort to increase the chance that at least one would make it to live birth.  Sometimes, “selective abortion” was practiced to reduce the number of initially multiple pregnancies to one.  Now, it appears that gradually increasing success rates of IVF are supporting single-embryo transfer as a standard practice.

The Centers for Disease Control and Prevention (CDC), which provides a substantial amount of information on the current status of IVF on its website, summarizes the changes in the percentage of single-embryo transfers in recent years—increasing from 11.6% of non-donor-egg transfers in 2007 to 39.9% in 2016.

To the extent that this reduces the practice of selective abortion and, one hopes, decreases the number of embryos created but kept frozen, never to be born, at IVF clinics, this is a welcome development.  The Christian Medical Dental Association takes the position that, in IVF, the number of embryos should be kept to a minimum, and all embryos created should be so created with the intent of having the genetic mother carry all of them in pregnancy, to live birth one hopes.

IVF remains a transformative enabling technology that facilitates contractual arrangements for reproduction, profound changes in the structure of families, and the use of pre-implantation genetic diagnosis to control what sort of people are allowed to be born.  One might view these developments as non-physical harms, that alter our overall experience of being human in ways that may properly be subject to question.

And: the rate of twin birth is still twice what it was in 1980.  If one sees a mom or dad pushing a stroller with fraternal twins, chances are they are IVF kids.