Scientists split over value of moratorium on editing the human germline

Michael Cook
March 20, 2019
Reproduced with Permission

The most dangerous weapon in the arsenal of biotechnology may be human germline engineering. Using a new technique for genetic editing called CRISPR, biologists have successfully altered the DNA of generations of plants and animals. Now they have their sights set on tinkering with human beings.

The possible outcomes range from modest (eliminating genetic diseases) to controversial (manufacturing “designer babies”) to bizarre (creating Humanity 2.0, an entirely new species of humans).

None of these are imminent, but they edged a bit closer late last year when Chinese scientist He Jiankui announced that he had edited the genome of two babies in order to make them immune to HIV/AIDS. There was an outcry from scientists around the globe that this was completely unethical. The Chinese government denounced his research and Dr He disappeared from view. He could be in prison; he is certainly in disgrace.

But the debate over the Chinese experiment is far from over. Biologists have split into two camps over the future of germline engineering: those who favour proceeding with great caution and those who favour proceeding with caution. But none of the major figures in the field see an objection, in principle, to resculpting what UNESCO has called “the heritage of humanity”.

In the latest development, several scientists called for a global moratorium on heritable genome editing in the leading journal Nature. This would not be a permanent ban but simply 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 moratorium would last five years. Thereafter clinical applications would be permitted provided that they fulfilled three conditions. These are: a robust international debate; a well-informed judgement that the application is justifiable; and a social consensus.

However, the names of a number of prominent scientists were conspicuous by their absence from the proposal.

One of the inventors of CRISPR, 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 its duration is unknown; and that it is unclear who has the authority to end it.

But differences over the moratorium are a sideshow to the daunting ethical question in the big tent: should human germline engineering be permitted at all? Nearly all biologists believe that it should be. “At this stage, no outcomes should be foreclosed,” write the scientists in favour of a moratorium -- provided that they can be justified on the grounds of safety, efficacy, benefit, and societal support.

Both sides agree that safety is a real concern. At the moment we do not know enough about how the genome works. Altering one part of an organism’s DNA can lead to complications in a number of other areas. For example, He Jiankui blocked a gene called CCR5, through which the HIV/AIDS virus invades human cells. But CCR5 also seems to protect against West Nile virus and influenza. So, while the experiment made it less likely that the children will get AIDS, it made it more likely that they could contract other diseases.

It is disturbing that safety alone is scientists’ central concern. The fundamental reason for a ban on altering the human germline is an ethical one – even though there is plenty of room for debate over the whys and wherefores. Scientists are moving faster than philosophers in their reflections. But here are a few issues that need to be addressed.

Most obviously, germline engineering changes the lives of generations to come without their consent. It assumes that scientists and doctors know what is best – and that’s not always true. It is the tyranny of the present over an unborn future.

On a personal level, it threatens to change what it means to be a human being. With natural conception, each person experiences his existence as a gift. If you are religious, you might acknowledge it as a gift from a beneficent God. If you’re not, it is still a gift from the wisdom of evolution, which has had hundreds of millions of years of experience in creating a successful genome.

The point is that a genetically modified human will experience his existence as the handiwork of other people. The reality of our lives is that we are dependent, contingent beings. The life of a person who owes to technology everything that he is will be different. Life as a human artefact will be different psychologically and well as physically in unforeseeable ways – especially if the modification does not work. What if genetic enhancement for high intelligence leads to early dementia?

From a social perspective, it’s inequitable. It will almost certainly create a market in genetic modification. If some of these are successful, they could create two classes of human beings – the gene-rich and the gene-poor. The wealthy will be able to afford tweaks which make their children more intelligent, better looking, or more athletic. The poor won’t.

Furthermore, it will inevitably lead to eugenics, the philosophy of improving the human race through genetics. As the official ideology of Nazi Germany, government-sponsored eugenics led to the deaths of millions. Consumer eugenics leading to designer babies may seem far from the atrocities of World War II, but the underlying impulse is the same – to “reduce individuals to their genetic characteristics and [not] to respect their uniqueness and diversity”, in the words of the Universal Declaration on the Human Genome and Human Rights.

Another ethical issue which gets lost in the debate over gene editing is that modifying the human genome will result in the destruction of countless human embryos. Unfortunately, few stem cell scientists take this waste of human life seriously.

For all of these reasons, governments should resist the demands of researchers who claim that germline engineering is both necessary and inevitable.

In a democracy scientists are not the arbiters of what is socially acceptable; voters are. The human genome should not be the plaything of curious scientists. As the UN says, it is “the heritage of humanity”. Rather than shilly-shallying about a moratorium, the most ethical response to proposals for human germline modification is for governments to ban it entirely.