Genetic modification of the human germ line has been widely banned internationally for many years on both safety and ethical grounds. But now a leading UK bioethics institute, the Nuffield Council on Bioethics, has published a major study of the ethical and practical issues, concluding that germ-line modification is morally permissible (Genome Editing and Human Reproduction, July 2018). I predict that this is the first step on the road to the introduction of germ-line modification in the UK.
The human body contains two types of cells: somatic cells that constitute the body’s tissues and organs (muscle, kidney and so on) and germ line cells that produce sperm cells in the male and egg cells in the female. Genetic modification of a somatic cell affects that cell’s performance in some defined way, and this modification will last throughout the lifetime of the bearer of the cells, but will not be passed on to the bearer’s offspring. On the other hand, genetic modification of the germ line will also pass on to all future descendants of the original germ-line-modified-person.
The discovery of the structure of DNA in 1953, the elucidation of the genetic code in the 1960s and subsequent development of techniques for transferring genes between organisms, paved the way for the development of sophisticated gene-editing techniques. There are endless practical applications of genetic modification, from agriculture to human health.
Banned in 40 countries
There are few ethical objections to using somatic cell genetic modification to cure disease. However, modification of the human germ line is banned in about 40 countries worldwide, including 15 out of 22 countries in western Europe, for reasons of safety and ethics.
Safety considerations refer to unintended consequences. Gene-editing techniques are not yet reliable enough to always absolutely ensure the precise achievement of the intended genetic modifications. While such techniques are acceptable for somatic cell genetic modification, they are not reliable enough for germ-line modification, where the induced genetic changes persist through future generations.
But gene-editing technology is developing rapidly and will soon be surgically precise enough to allay all reasonable fears about safety. Opposition to germ-line modification will then rely solely on the ethical grounds I will now summarise.
The human genome, shaped by evolution over millions of years, is the essence of what we are. If anything physical could be deemed sacred, it would surely be the human genome, and the idea of widespread tinkering with it elicits deep feelings of unease in most people.
Then there is the question of consent. Before undergoing genetic modification of somatic cells to cure a problem in an organ/tissue, I can freely consent to the procedure. But the people who will be affected by germ-line modification do not exist yet and cannot give consent. Is it right to impose this change on them?
Personal improvement
Arguments for germ-line modification concentrate heavily on its capacity to eliminate genetic disease. However, in this respect, germ-line modification presently offers no greater benefit than existing technologies such as preimplantation genetic diagnosis and in-vitro fertilisation.
Furthermore, if germ-line modification were in routine use to eliminate disease, demand to use it for the purposes of personal improvement (such as IQ, athletic build) and for cosmetic enhancement (for example, hair/eye colour, nose shape) would surely arise. Also, the expense of germ-line modification, enabling wealthy people to buy much more of it than poorer people, risks the rise of a “biological elite”.
Although I wouldn’t rule out germ-line modification in principle, the ethical considerations described above persuade me that we should not introduce it any time soon.
You might think that these ethical objections combined with the widespread public opposition to genetically modified food in Europe would rule out public acceptability of genetically modified human beings. But I don’t agree. I expect that the maxim – if it can be done, it will be done – will play out in due course.
I expect that, before long, human germ-line modification will be gradually introduced and, unless serious early failures are registered, will quickly win public acceptance. Notions about the inviolable human genome will not survive.
A powerful new eugenics will then move centre stage. The last popular eugenics movement spawned a nightmare. Will history repeat itself?
William Reville is an emeritus professor of biochemistry at UCC