Opinion, Berkeley Blogs

The international summit on human gene editing

By Charis Thompson

An International Summit on Human Gene Editing, co-hosted by the U.S. National Academy of Sciences and National Academy of Medicine, the UK’s Royal Society and the Chinese Academy of Sciences, took place Dec. 1 to 3, 2015. We speakers were charged with addressing the scientific and ethical challenges posed by the new accurate and accessible genome editing technologies, such as CRISPR/Cas9 applied to human genomes.

The most pressing task of the summit was to consider whether human germline genome editing should be allowed. Edits to someone’s germline genome are deletions and/or insertions of small segments of DNA in germ cells (eggs and sperm or their precursor cells, pluripotent stem cells, or very early embryos to be used in reproduction). These alterations would be carried into all the cells of a resulting child, and then passed on to future generations through sexual reproduction.

Although such edits might cure severe disease in the resultant child, the risk of errors and unintended effects to the child and from spreading genome changes into the gene pool are unknown and, to many, unacceptable. Somatic human gene editing, on the other hand, treats an already existing patient for the disease symptoms she has, raising far fewer concerns.


A range of positions on human germline genome editing emerged over the two and a half days. They fell into “yes” positions, which were in favour of giving the green light to human germline genome editing under the right conditions, and “no” positions, which were against permitting human germline genome editing at this time or ever. I summarize these positions below.

“Yes” to human germline genome editing, in order from the most to the least permissive:

  1. Edit the human germline genome for reproduction if it is no more risky than “natural” sexual reproduction and is aimed at eliminating serious genetic conditions.
  2.  Edit the human germline genome for reproduction if it is likely to be safe, effective and make a big difference. (For example, for monogenic/oligogenic serious medical conditions.)
  3. Edit the human germline genome for reproduction to avoid having offspring born with a serious condition only if there are no other alternatives, such as in vitro fertilization with pre-implantation diagnosis. (For example, if both genetic parents are homozygous for the same serious medical condition so that none of their embryos would otherwise be free of the condition.)
  4. Move toward editing the human germline genome for cultural and religious reasons, such as when a given national culture is pronatalist, has a pro-medicine ethos, and has significant state subsidies for reproductive and screening technologies.
  5. “No” to human germline genome editing, in order from the most to the least permissive:

    1. Hold off (place a moratorium) on editing the human germline genome for reproduction while we work out the technical issues of safety, off-target effects, efficacy, efficiency of the edit, and the development of a clinical grade delivery mechanism for the editing system.
    2. Hold off (place a moratorium) on editing the human germline genome for reproduction at least until we (re)frame and make much more inclusive vital ethical, social, and economic debates around ableism and disability justice, the over medicalization of human variability, racism and sexism in science, local and global health inequality, the views of non-stakeholders as well as stakeholders, and the needs of future generations, the vulnerable, and other species.
    3. Ban the editing of the human germline genome for reproduction because it is a reasonable line to draw against hubris and in favor of our human future, against a highly likely slide toward eugenics and the exacerbation of inequality, and against possible ecological and other harms.
    4. Ban the editing of the human germline genome because of the moral status of the embryo, human dignity, the freedom rights of the genome-edited child, and/ or religious conviction.
    5. Together, these eight positions reflect disciplinary and sector commitments, but they are all well-thought out, and all reflect strongly held values. In my opinion, there was a surprisingly high level of consensus collecting around the two “hold off” positions, and the fact that the social and technical issues came together here is promising for regulation in the area.

      At least two big challenges remain in terms of process. The first is to get better at hearing what others are saying and thinking, including soliciting the views of many more constituencies, so as to avoid false dichotomies, such as those between science and ethics, and moving ahead or slowing down the science. The second is to put in place robust mechanisms of accountability for both the social and technical concerns expressed at the meeting.

      Widely representative committees need to be formed to take regular stock of the field’s safety and efficacy, and of its impact on social justice and a better life for all. The National Academies’ work is just beginning.

      Crossposted from Impact Ethics.