Hoofdstuk V: The status of the human genome: is it ever licit to modify an individual’s genome?

Het embryo - iets of iemand ?Hoofdstuk V uit “Het embryo: Iets of iemand?”, onder redactie van mgr.prof.dr. E. Sgreccia e.a., Colomba, 1997
door P. Garrett, M.A.

The human genome is a biological entity which comprises the three-billion-letter genetic code contained within the nucleus of the typical human cell. The biological raw material of the genes which contain this genomic information is the deoxyribonucleic acid (DNA) molecule. This molecule is best envisaged as a twisted ladder, with uprights composed of chains of sugar and phosphate groups, while the rungs consist of bases sticking inwards towards each other. These rungs of the DNA ladder form properly only when one pyrimidine base plugs into one purine base, which results in fixed proportions of one adenine to one thymine, and one cytosine to one guanine pertaining throughout the genome. These organic bases, along with their ribonucleic acid (RNA) cousin uracil, encode a1l the information which makes us into physical human beings.During the 1960s, geneticists discovered that the chromosomes are not uniform but are made up of coding sequences which specify proteins, ‘control’ sequences (acting as switches for structura1 genes) and areas which contain base pair sequences with no obvious function. We now believe that the human genome contains 80-90,000 actual genes which code for proteins.

The high-profile Human Genome Project seeks to ‘write out’ the entire sequence of genetic letters: those which generate the proteins that constitute our physical bodies (exons) and those other sequences which do not (introns). When this task is completed, clinical geneticists will search out genetic ‘spelling mistakes’ as a prelude to genetic engineering treatments. Technologies will then be developed not only to repair dysfunctional parts of the genome, but also to enhance ‘normal’ ones. The technological barriers in this area are considerabie, but so is the scientific motivation to overcome them. It will be important to refer back to this repair/enhancement distinction later when discussing the ethical status of the genome.

At this early stage the Human Genome Project is ‘merely’ trying to produce a standardized human genome which will not be the genome of a particular individual. Around the year 2010, human genome studies will progress to the analysis of multiple genomes, belonging to specific individuals, and the developing fields of genetic screening and genetic counselling will have to struggle to come to terms with the implications of this.

1. Status of the human genome
Looking at the ethical status of the human genome, one approach is to proceed by analogy with the debate over the ontological and moral status of the human embryo. Indeed, this was the approach taken by the Cathollc philosopher Luke Gormally when he was asked to speak on the status of the human genome in Rome, in 1995. (1)

For Gormally, the individual human genome. should be thought of as the fundamental information-bearing structure, within a complex organ of development and heredity, through which an organism exercises its natural powers of growth and reproduction. The functions of this genome have a determinate role in the formation of the human body, and an essential role in the transmission of an organized body of specific potentialities wich are apt for actualisation in a living human being through God’s creation of a rational soul.

Gormally argues, and I think rightly, that the ontological status of the human genome is rankable somewhere between that of the human embryo and that of a single human organ. Thus, while we do not owe a duty of care to a particular human organ, we do owe such a duty to a human embryo. According to Gormally, it is possible to locate the moral status of the genome somewhere between these two extremes.

Clearly, such an analysis affords an important role to the human individual’s genome and allows concepts and argument to be imported analogically from two well-developed areas of moral philosophy.

In order to make this qualitative comparison more precise, Gormally goes on to remind us of the ‘causal role’ wich each individual genome plays in a person becoming the living bodily being he is. By equating acceptance of the life given through parents, to acceptance of a particular genome, Gormally leaves us in no doubt as to the ontological and moral importance of each individual’s genome. In fact, Gormally’s understanding of the genome’s status leads him to formulate a significant final statement: “I have come to think that understanding what [the genome] is gives us some reason for thinking that modifications of the genome designed simply to alter non-pathological limitations are contrary to moral wisdom”. (2)

This allows that genetic modification may be licit as long as it aims at the correction of a pathological limitation. This type of demarcation will roughly equate to the separation between curative and enhancement engineering and will necessitate a close definitional analysis of the term pathological. This refined analysis is to be welcomed, but will always leave a grey area between the pathological and the non-pathological. Gormally is right to remind us that those who destroy the distinction, or abandon the intellectual effort of distinguishing, ‘destroy the possibility of thinking coherently about what is required for acceptance of the particular bodily life which each of us has been given.’