Moreover, with the completion of the basic sequencing of the human genome this year, opportunities for screening are likely to expand rapidly. The dilemmas begin at the point when a test for genetic susceptibility to a disorder becomes available, and each person needs to decide whether to undergo testing. Currently, testing is generally targeted at people who appear to be at higher risk for a disorder. Existing research suggests great individual variation in the extent to which people want to know that they are carriers of alleles that increase their risk for a disorder. The benefits include early diagnosis and treatment for some disorders, as in the case of the BRCA1 allele.
Couples can also make more informed decisions about having children of their own.
But many people don't want to know about the genetic liabilities that they carry, fearing the anxiety that the information will cause and the damage to their self-concept. For instance, the availability of tests for genes that make small contributions to the probability of a disorder, as will occur in conditions that have a polygenic basis, will provide little useful information about the risk faced by any individual. This is likely to be the situation we face as we learn more about the genetics of mental disorders. In such cases, it is difficult to argue in favor of a moral imperative for testing. If a person decides to go ahead with testing, a new set of issues about disclosure within the family arise.