Someone I know was recently diagnosed with Huntington's Disease, sometimes known as Huntington's Chorea, and it got me thinking about some really perplexing moral dilemmas posed by the disease. Huntington's, for those of you who do not know [there is a long and very informative article on Wikipedia, if you are interested] is a genetic disorder that afflicts between 5 and 10 persons per 100,000 worldwide, with Europeans much more likely to have it than Asians or Africans. It is genetically dominant and not sex-linked, which means that if either parent has the gene on one chromosome [and hence will eventually come down with the disease, since it is dominant], a child has a 50% chance of having the disease as well. If each parent has the gene on one chromosome, the probability is 75%, and if either parent has the gene on both chromosomes [a rarity] the probability of each child being affected is 100%. Note that because the genetic disorder is dominant, it is not possible to inherit it from parents neither of whom develops the disease [assuming they live long enough.]
The disease causes increasingly severe motor problems, cognitive problems, and eventually dementia, leading to death. Although there are cases of the disease appearing in childhood, it typically becomes manifest in young or middle-aged adults [which is to say, at or after child-bearing age]. There is no cure, and although drugs can to some extent ameliorate the symptoms, especially in the early phases of the disease, its progress is inexorable. Life expectancy after the initial manifestation of the disease is about twenty years.
The moral dilemmas are obvious: Should parents who know that they are gene carriers tell their children? Should they have their children tested? Should adults who know they are at risk for being carriers [and hence eventually sufferers from the disease] have themselves tested before they have children, and if they are carriers, should they have children at all? Is someone who knows that Huntington's runs in the family obligated to tell a partner before marriage or procreation? Does that person have a responsibility to be tested before entering into a committed relationship that might result in children?
There is virtually no medical advantage to be gained for the individual from genetic testing, since knowing that one has the gene does not make it possible to do anything at all to lessen the inevitability of developing Huntington's. To tell a child or young adult that he or she has the gene is to give that person a very hideous death sentence, albeit one that may not be imposed for several decades. But knowing that one has the gene would allow a man or woman to deliberate about whether to have children, inasmuch as there would be a 50/50 chance of passing the disease on to each child.
One of the peculiarities of a genetic disorder like this is that it can be eliminated from the human genome in one generation if every carrier chooses not to reproduce. Although an incidence of one per ten thousand [more or less] is very low, in a population of three hundred million, one would expect to find perhaps 30,000 persons who have manifested or will manifest Huntington's at any given time. From a Public Health perspective, eliminating such a genetic disorder from the human genome would seem to hold out the prospect of avoiding a very great deal of human suffering.
So, there are the dilemmas [and many more, which I am sure my readers can conjure up.] I have to confess that I have very few secure moral intuitions about this matter. The one thing that seems obvious to me is that anyone who knows that he or she is at risk for carrying the gene has a moral responsibility to be tested before contemplating procreation. It also seems to me clear [although perhaps not quite as clear] that such a person ought to inform anyone with whom he or she is considering entering a relationship that might lead to procreation.
I would be very curious to know what folks think about this.