24 September 2020

Not everyone will be taken into the future

To whom and how will the genetic editing of children be allowed

Polina Loseva, N+1

After a year and a half of reflection and meetings, the International Commission on the Clinical Application of Genetic Editing has issued a 200-page report and 11 recommendations for WHO. In short, the position of the scientific community sounds like "embryos can be edited, but". N+1 analyzes the report and tells what lies behind these "buts", who, according to scientists, can be treated with CRISPR / Cas9 and what the Russian frontman thinks about it in the field of creating GM children.

Now you can

Fifteen and a half years ago, the UN called on the states of the world to ban human cloning, or more precisely, "to ban all forms of human cloning to the extent that they are incompatible with human dignity and the protection of human life." And despite the fact that the second half of this formulation sounds ambiguous and leaves it to each country to decide independently what is compatible with human dignity and what is not, the UN position from the very beginning was unambiguous: "refuse and not let".

Many countries (for example, Russia) imposed a ban on cloning even before the UN resolution, and in others (as in the USA) there is still no corresponding federal law. But, one way or another, drastic measures worked: we have never heard of cloned people (and perhaps it's worth thinking about why, because the technology is known).

Now we have a new molecular tool that has not yet been written into any laws – genetic editing of the germ line. We have to think much faster: genetically modified people have already been born. And although their names are still unknown, the scientific community does not doubt their existence - and the court verdict of their "creator", Jianku He, was a confirmation of this.

The question of whether to ban the editing of embryos entirely was not raised from the very beginning – unlike cloning, there are too many possible applications, the potential gain is too high. This was clear from the first meetings of the International Commission of Scientists, which met shortly after the He scandal. And now, when, after a year and a half of meetings and discussions, the Commission has finally published its proposals, they look more like a resolution. It will be possible to edit children – but under certain conditions. The question now is how realistic it is to meet these conditions.

Moving the fence

The real task that the Commission faced was to draw a line between permissible and unacceptable applications of the new technology. Judging by the disputes that broke out in 2018 after the He report, and then again in 2019 – when the Russian biologist Denis Rebrikov appeared on the scene – each scientist draws this boundary for himself in his own way.

Some believe that embryo editing should still be banned definitively, regardless of the goals – this is how one of the developers of the CRISPR/Cas system, David Liu, reacted to the commission's report. Others, on the contrary, are not against interfering with human DNA – for example, Harvard biologist George Church has repeatedly made it clear that editing can prevent many diseases and give people new abilities.

A few years ago, Church's colleague George Daly mapped all possible genome intervention targets on a continuous scale. On the left there were "obviously justified" ones, like preventing severe genetic diseases, and on the right – controversial, potentially dangerous ones, which Daly called "improvements" (eye color, height, muscle mass, intelligence, and so on). In the middle is a reduction in risk – for those diseases that may not meet on the path of a person, but if they do, they will cause serious difficulties. Among them were cancer, HIV and pandemic resistance (which today looks like a fateful prophecy).


Most of the scientific community defines the threshold of acceptable applications somewhere in the middle of this scale. Among those who admit the possibility of genetic editing of children, not everyone plans to improve intelligence. But disputes invariably flare up around each specific disease: is the damage really worth the risks? Is it really impossible to prevent it in another way?

In an attempt to put an end to these disputes, the Commission put forward four specific criteria that each case of gene editing should meet.

  1. It must be a serious monogenic disease.
  2. As a result, the pathogenic variant should turn only into a "healthy", well-known and widespread in the population (this bar should immediately cut off crazy ideas like implanting a slow-walking gene in a person).
  3. Embryos without a pathogenic variant should not be edited.
  4. Editing can be carried out when parents have no chance of conceiving a child without a genetic disease, or their chances are low (25 percent or less), and they have already made at least one unsuccessful attempt.

Further in its report, the Commission divided all possible cases of editing into six groups to check how each of them meets these requirements. And here the most interesting thing begins.

How important it is to be serious

Groups A and B include situations where all or part of the offspring of the parents will inherit a serious monogenic disease. Group C includes monogenic, but not serious diseases. Group D unites polygenic diseases, group E – situations of "improvement" of people in the same way as Church understood it (to give people new properties or get rid of some possible diseases like HIV), and, finally, group F – monogenic diseases that cause infertility.

With monogenicity, everything is clear – these are the cases when the presence of one or two (depending on the type of inheritance) mutant copies of the gene definitely leads to the development of the disease. There are many examples of such diseases, but the Commission mentions only a few (probably hinting that they look like worthy candidates for editing): muscular dystrophy (probably referring to Duchenne dystrophy), beta-thalassemia, cystic fibrosis and neurodegenerative Tay-Sachs disease.

It is much more difficult to find out which disease is considered serious. The Commission recognizes that there is no single concept of a "serious" disease, and each regulatory authority in each country has to define it in its own way. Within the framework of this report, scientists understand a "serious" disease as one that "causes severe clinical manifestations and premature death."

In addition to the classic examples of genetic diseases mentioned above, the Commission proposes to include Huntington's disease (which, however, no one yet knows how to treat with CRISPR/Cas9), a hereditary form of early Alzheimer's disease and at least one type of cancer – familial adenomatous polyposis.

At the same time, the report specifically states that hypercholesterolemia (which He also tried to "treat" at one time, but his work was not accepted for publication) is not considered "serious" and belongs to category C, as well as hereditary deafness – a clear warning to Denis Rebrikov. For these diseases, according to the report, there is a treatment that levels the risk of premature death. "The decision of a particular country (and we can guess what kind of country it is, although it has not yet issued permission for editing to Rebrikov – N+1) on the issue of genome editing," the Commission writes, "in cases such as deafness, raises many complex issues that are beyond consideration of this report."

Rebrikov himself predictably disagrees with this approach.

"It's right to start with the most severe cases that exist," he argues in correspondence with N+1. – Of autosomal recessive (which manifest themselves when both genes are "broken" in a person, so two carriers cannot have a healthy child - N+1) monogenic diseases with a non–zero probability of the existence of families are dwarfism and hereditary hearing loss."

All other diseases, according to the scientist, are either much milder, or almost never allows people to live to puberty and start a family.

And indeed, according to the report, the average occurrence of families with the same mutation is 4-8 per ten billion (unless mutations for some reason have accumulated in a separate population, as happens, for example, with Tay–Sachs disease, which is more common in Ashkenazi Jews). In such a situation, it is not very clear how to recruit 10-20 families that the Commission requires as a sample for the first clinical trials of the new technology.

In addition, among the examples that appear in the report, almost no disease exists in families. Carriers of the Tay-Sachs syndrome usually die as children, Duchenne myodystrophy – as teenagers. People with cystic fibrosis in developed countries live to reproductive age and even give birth to children, but reports of such families are extremely rare. There remains only beta-thalassemia, which in a mild form allows you to live a full life – and in this case, the severity of this disease can be compared with deafness.

Needless to say, the more exotic applications of genetic editing – groups D, E and F – did not deserve even a detailed discussion in the report. The Commission does not rule out that one day they will become possible, but admits that it has not figured out how it could be regulated in principle.

The exception is group F, for which scientists have proposed a possible solution – to edit individual germ cells (gametes). Theoretically, they can be grown from the stem cells of a particular patient – which means they can be obtained in large quantities, carefully check the safety of editing and not be afraid of mosaicism in the bud. But this way does not solve all the problems. To test the effectiveness and safety of such editing, Rebrikov believes, you will still have to create and grow an embryo, "and this again turns out to be editing an embryo."

A dead end or a crossroads

Trying to get away from the continuous scale on which everyone defines their place in their own way, the Commission drew a new scale with its report. There is no longer room for "improvements" in human nature and innate protection against HIV, but there is a lot of room for discussion about the severity of the damage and the degree of "severity" of each specific disease for which a key gene has been found or has already been found. And if the recommendations remain in the same form as they are now, the final decision in each case will remain with the countries' own regulatory authorities.

However, everything can still change, since this report is only the position that the scientific community declares and the advice that it addresses to WHO. At the next stage, it will have to accept, reject or finalize these lists. So far, WHO representatives are silent and do not comment on the report in any way. The Organization has its own Commission, which will deal with international regulation, but according to its website, it is still busy creating a database of clinical trials using genome editing technologies.

Denis Rebrikov is pessimistic and believes that WHO "will try to ban everything." But anyway, while there is no final ban on genetic editing, any use of it is theoretically possible – if only to present a specific gene variant and prove that its presence exposes a person to a sufficiently "serious" risk.

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