Germline genetic engineering alters the genes in sperm or egg cells (or their immediate precursors), the zygote, or the early embryo. The usually stated goal of such genetic modifications is the same as somatic genetic engineering, i.e., to correct (or prevent) a disease state caused by a defective gene.
In simple terms, human germline intervention is the process of editing an individual’s genome to interrupt the genetic transmission of heritable conditions and traits.
The word “germline” has nothing to do with harmful microbes, which is typically what we mean when we use the word “germs”. A germ cell is any cell which gives rise to the gametes of a biological organisms which reproduces sexually. Germline engineering typically involves the alteration of the genes in germ cells – or of the reproductive cells themselves – to bring about a specific change which is heritable. When we talk about germline intervention, we are talking about intervening to prevent the continued transmission of heritable diseases by altering the genome of germ cells or reproductive cells.
Some researchers are warning that germline engineering is a lot closer to becoming a reality than people typically realize. Gene therapies are well beyond a theoretical possibility, with many gene therapies already being put into action against numerous conditions. Similarly, our understanding of how a genome may be altered has leapt from theoretical discussions to practical trials, many of which have been resounding successes.
As such, many leading figures in biotechnology are demanding a frank confrontation of the potential consequences of germline intervention on our society. That germline engineering will have profound ramifications for humanity is not difficult to accept; being able to selectively edit the genome will give us unparalleled control over our genetic present and our genetic future. In effect, successful, reliable germline engineering will give us complete control over the human future, at least in a biological sense.
The problems that would spring out of this technology are largely obvious. Much like the racist obsession with eugenics in the nineteenth and twentieth centuries, germline intervention would be a rallying point for racially-focused ideologies in this century and beyond. On a more practical level, questions about who would have access to germline engineering, what kinds of alterations could be made, and which alterations would be barred will arise.
The phrase “genetic engineering” can be used to refer to two very different things. Somatic genetic engineering targets somatic (body) cells, and can also be called genomic medicine, since it is in effect traditional medicine at the level of the genes. It affects only the individual who is treated. Germline genetic engineering, however, makes possible changes that will spread to every subsequent generation. It can also be called inheritable genetic modification, and has the potential to change the human species along eugenic lines. Princeton biology professor and biotech enthusiast Lee Silver has written of a future in which the “GenRich,” who are the descendants of those with “improved” germlines, may be so distinct that they will not even be able to have children with standard human beings. It is this prospect that has led some writers to look ahead using the terms “transhumanist” and “posthumanist,” and others to speak of the “abolition of man.” And it has led the nations of Europe, in the first international bioethics convention (the European Convention on Human Rights and Biomedicine), to outlaw germline changes altogether.
The somatic/germline distinction is vitally important, and focuses attention on the dramatic implications of the “genetic engineering” of embryos, sperm or egg cells or their immediate precursors, i.e., the germ cells. Germline genetic engineering alters the genes in sperm or egg cells (or their immediate precursors), the zygote, or the early embryo. The usually stated goal of such genetic modifications is the same as somatic genetic engineering, i.e., to correct (or prevent) a disease state caused by a defective gene.
However, germline genetic modifications affect prospective individuals, including not only the ones who are engineered, but also all their descendents. Both techniques could be abused—either could be used for enhancements of genetically-determined abilities, as opposed to therapeutic treatments for disease. Germline genetic engineering also can allow for the selection of genetic characteristics in a prospective child, producing a “designer baby” with desired traits. More broadly, it could lead to the “re-designing” of the human species.
On top of all this, we will have to deal with the ethical problems that come with genetic engineering on this scale. It is unquestionable that germline intervention allows us to make very specific decisions about the future biology of the human race. This will raise questions about how far we are able to actively interfere with the autonomy of future generations, and how much we are able to “play God”.
Of all of these, the most pressing problem that will come with germline engineering is socioeconomic – not everyone will have access to germline interventions at the same time or to the same degree. It is therefore exceedingly likely that germline intervention will act as an accelerant to the already burning flame of inequality and racial divisions. If the rich developed nations employ germline intervention to enhance their citizens’ health and performance, then the rest of the world will be quickly left behind. Within those rich developed countries, there will be vast swathes of the population who cannot take advantage of germline engineering technology, and they too will be left behind as the economy storms ahead (with a healthier, more productive population).
So what can be done to head off the problems that will inevitably come with the expansion of germline intervention therapies?
Until we see germline engineering being practiced on humans, there is little we can do. But once this biotechnology is employed, it will need to be tightly regulated, monitored, and at least initially, confined to medical applications. While germline therapy can certainly be used for human enhancement, there will have to be a period of latency while we figure out, as a society, what to do with the untold powers which come with genome editing.