The question not asked: the challenge of pleiotropic genetic tests.

Nearly all of the literature on the ethical, legal, or social issues surrounding genetic tests has proceeded on the assumption that any particular test for a gene mutation yields information about only one disease condition. Even though the phenomenon of pleiotropy, where a single gene has multiple, apparently unrelated phenotypic effects, is widely recognized in genetics, it has not had much significance for genetic testing until recently. In this article, I examine a moral dilemma created by one sort of pleiotropic testing, APOE genotyping, which can yield information about the risk of two different conditions -- coronary heart disease and Alzheimer's disease. A physician administering APOE testing for the beneficial purpose of assessing the risk of heart disease may discover medically useless and socially harmful information about the patient's risk of Alzheimer's disease. I explore how much providers should disclose to patients about pleiotropic test results and whether patients are obligated to know as much about their genetic condition as possible.