February 25, 2024

Scientists split over value of moratorium on editing the human germline

After the Chinese scandal, there are renewed calls for a global halt

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Stem cell scientists have split over the future of genetic editing of the human germline. In a commentary in Nature several leading scientists have called for a global moratorium on heritable genome editing. This would not be a permanent ban but an international agreement not to greenlight germline editing leading to pregnancies “unless certain conditions are met”. The proposal was strongly backed by Francis S. Collins, the director of the US National Institutes of Health.

The proposal was motivated by the outcry following an experiment by Chinese scientist He Jiankui which resulted in two babies whose germline had been edited. It was subsequently learned that some Western scientists knew about his work and had even collaborated in it.

However, the names of a number of prominent scientists were conspicuous by their absence on the call for a moratorium.

One of the inventors of CRISPR, the revolutionary gene-editing technique, Jennifer Doudna of the University of California, Berkeley, told STAT that she supports “strict regulation that precludes use” of germline editing until scientific, ethical, and societal issues are resolved. “I prefer this to a ‘moratorium’ which, to me, is of indefinite length and provides no pathway toward possible responsible use.”

Similarly, Nobel laureate David Baltimore, of California Institute of Technology, Harvard Medical School Dean George Daley and Harvard biologist George Church do not want a moratorium. They believe that it cannot be enforced; that it is unclear how long it should last; and that it is unclear who has the authority to end the it.  

In fact, the scientists proposing the moratorium were by no means categorical about the fundamental question of the ethics of germline editing. “At this stage, no outcomes should be foreclosed,” they write. They seem to feel that it could go ahead, provided that it can be justified on the grounds of safety, efficacy, benefit, and societal support.

However, they do list a number of knotty ethical issues:

The societal impacts of clinical germline editing could be considerable. Individuals with genetic differences or disabilities can experience stigmatization and discrimination. Parents could be put under powerful peer and marketing pressure to enhance their children. Children with edited DNA could be affected psychologically in detrimental ways. Many religious groups and others are likely to find the idea of redesigning the fundamental biology of humans morally troubling. Unequal access to the technology could increase inequality. Genetic enhancement could even divide humans into subspecies.

Moreover, the introduction of genetic modifications into future generations could have permanent and possibly harmful effects on the species. These mutations cannot be removed from the gene pool unless all carriers agree to forgo having children, or to use genetic procedures to ensure that they do not transmit the mutation to their children.

The proposed moratorium to be imposed by governments on “any clinical use of human germline editing” would last five years. Thereafter clinical applications would be permitted provided that they fulfilled three conditions. These would be: a robust international debate; a well-informed judgement that the application is justifiable; and a social consensus.

It is essential to ensure that the public is consulted and informed. They conclude that:

Certainly, the framework we are calling for will place major speed bumps in front of the most adventurous plans to re-engineer the human species. But the risks of the alternative — which include harming patients and eroding public trust — are much worse.

Michael Cook is editor of BioEdge 

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