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02/23/2017

Still further on heritable human gene editing

I want to spend a little time—several consecutive posts—on the subject of heritable gene editing in humans, and on the recent report by the National Academies of Science, Engineering, and Medicine on it.  The topic bears more attention than a single blog post, written in a bit of a rush, based on only the initial release of the report, pending a deeper dive.  That is where I have been until now.

At the link above, one can download for free a pre-publication pdf of the full, book-length report.  (Last week I had found a 4-page summary that I can’t seem to locate again this week.)

Less than 15 months ago, in early December 2015, the Washington Post was reporting that “experts” were saying “It’s too early for gene-editing of human reproductive cells.”   Some, like Nobel laureate David Baltimore of Caltech, drew the line at attempting to establish a human pregnancy with an implanted embryo that had been gene-edited.  Others working in the field were writing that even a moratorium on laboratory studies of editing human sperm or egg cells was wise.  Then, as now, these experts (and they truly are experts, providing careful reflection for public benefit and guidance) were calling for more public input before pushing ahead.

Still, in a separate brief summary of the new report’s key points, the committee that prepared it says, first, that laboratory studies of editing human egg or sperm cells, the cells that produce them, or early human embryos “is essential to the advancement of science and should continue with[in] existing regulatory structures.

What has changed in less than 15 months?  May I suggest, nothing?  Last week, I used the words “runaway train.”  To be sure, I hear something of the same worry behind the experts’ just-released report.  In the 4-page summary I have, they write, that developing policies around human genome editing is “pressing, in large part, because of the…growing use of the CRISPR/Cas9 system.”  Growing use, as in, exploding.  I think we can concur with the committee about the urgency of the matter.

But, again, the experts seem to have moved from “don’t proceed with any pregnancies from this” to “clinical research trials could be permitted” only under a set of circumstances that are carefully controlled, at least to the extent possible.  In my post last week I copy-pasted their full list, the shorter form of which includes the following critera:

  • Absence of reasonable alternatives
  • Restriction to editing genes that have been convincingly demonstrated to cause or to strongly predispose to a serious disease or disabling condition
  • Availability of credible pre-clinical and/or clinical data on risks and potential health benefits of the procedures
  • Ongoing, rigorous oversight during clinical trials of the effects of the procedure on the health and safety of the research participants
  • Comprehensive plans for long-term, multigenerational follow-up while still respecting personal autonomy
  • Continued reassessment of both health and societal benefits and risks, with broad on-going participation and input by the public

IF one were going to allow attempts to, for example, prevent or “genetically cure” sickle-cell anemia prenatally, one would want to meet these criteria.  But suppose we could meet them all, except for of course the multigenerational follow-up, which would take time.  Suppose we knew beyond a shadow of a doubt that, in this case, the sickle hemoglobin gene mutation, a single point mutation, were definitively and selectively repaired in a new unborn human being, and we could treat a small but sufficient number to know that, at least into their young adulthood, they had no other adverse health consequences whatsoever, and maybe even had begotten unaffected infant children.  Would we consider this an unambiguous good?  I’m not so sure.  For one, we would have formed, in the first instance, an absolute dependence on in vitro conception—not that such is not the state of affairs in many cases, anyway.  But a mindset that “procreation the old fashioned way” is too dangerous would be fostered.

 

For another, the past and ongoing basic research would have included creation and destruction of human embryos—nascent human beings—for research purposes.  Well, maybe the horse would have left the barn, as is argued for the development of certain vaccines now widely in use.

 

The National Academies’ report focuses on human uses of gene editing—“gene therapy,” enhancement, and heritable changes.  Meanwhile, on the European continent, apparently they are not so sure whether they want to permit gene editing in plants.

 

And, of course, where there’s cutting edge science, there are patent applications, with an uncertain outcome in part because the techniques are already moving beyond CRISPR/Cas9.

 

More to follow on this.  In the meantime, interested readers may also want to revisit this short treatment of the topic.

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