A host of medical problems attend athletics, from acute events (eg, sudden death) to chronic conditions (eg, degenerative arthritis). There is increasing interest in genetically identifying athletes at heightened risk for morbidity or mortality. The focus has been on uncommon disorders caused by mutations in single genes. Eventually the focus will expand to include multifactorial conditions, such as coronary artery disease. Genetic testing, even for Mendelian disorders such as Marfan syndrome, familial hypertrophic cardiomyopathy, and the long QT syndromes, is more complicated than other forms of testing in medical practice, and involves issues of analytic and clinical validity, clinical utility, cost, discrimination and stigmatization. Moreover, genetic testing requires pretest and posttest counseling that either is ignored by practitioners or is beyond their current level of understanding...