Harvard Medical School
The decision about whether or not to be tested is ultimately yours, and yours alone, to make. You are a competent adult, and you have the right to make autonomous decisions about your body and your health care. You are entitled to know this information, just as you are entitled to know your blood type or your blood cholesterol levels. The information is within you, and it should not be kept from you.
Some might say, however, that beyond a right to know, you have a duty to know—that you ought to find out whether or not you will get the disease. You ought to be tested, they might say, so that if you do have the gene, your family can prepare for your illness, or you can avoid having a child that might also carry the gene. But this is surely misguided on both counts.
What does it mean, we might ask, to have a moral duty to do anything? This is an important and inscrutable question—the central question, in fact, of the branch of philosophy called ethics—and many people have answered it in different ways. But in your case, we may say that you have a moral duty to do what you believe will result in the greatest amount of good and the least amount of suffering for you and your family. If you have the gene, and you believe that you and your family would suffer less by knowing now rather than later, it is true that you have a moral duty to be tested. If, on the other hand, you feel that you and your family would suffer more if you know the results now—if you fear that the knowledge would harm your marriage, or estrange you from your siblings—then you have a moral duty not to be tested. It is certainly premature, then, for anyone to tell you, prima facie, that you have a moral duty to be tested for the huntingtin gene.
In the same way, it is premature to say that you have a moral duty to keep from passing the gene on to your children. It is a serious thing to bring a child into the world who might suffer as your mother suffered. You may decide not to take that chance. But to consider it wrong, or to try to prohibit it, is unconscionable, vaguely reminiscent of the time when our government sterilized mentally handicapped people to keep them from procreating. Can we really presume that Huntington disease carriers would rather not have been born? Does the suffering in their lives outweigh the good which might derive from them? What if your mother, aware that she carried the gene and faced with a similar decision, had chosen not to give you birth? Would that have been a good thing or a bad thing? Is the potential suffering of a person too high a price to pay for his or her existence? These are tough questions, for you alone to decide; and only you can know if you ought to be tested.
Kinghorn W. Indecision. JAMA. 1998;280(17):1538. doi:10.1001/jama.280.17.1538-JMS1104-6-1