The ability to sequence individual genomes is leading to the identification of an increasing number of genetic risk factors for serious diseases. Knowledge of these risk factors can often provide significant medical and psychological benefit, but also raises complex ethical and social issues. This paper focuses on one area of rapid progress: the identification of mutations causing long QT syndrome and other cardiac channel disorders, which can explain some previously unexplained deaths in infants (SIDS) and children and adults (SUDS) and (...) prevent others from occurring. This genetic knowledge, discovered posthumously in many cases, has implications for clinical care for surviving family members who might carry the same mutations. The information obtained from genetic testing, in the context of personal and family history, can guide individually tailored interventions that reduce risk and save lives. At the same time, obtaining and disclosing genetic information raises difficult issues about confidentiality and decision making within families. We draw on the experience of the Montefiore-Einstein Center for Cardiogenetics, which has played a leading role in the genetic diagnosis and clinical management of cardiac channel diseases, to explore some of the challenging ethical questions arising in affected families with adolescent children. We focus on the related issues of (1) family confidentiality, privacy and disclosure and (2) adolescent decision making about genetic risk, and argue for the value of interdisciplinary dialogue with affected families in resolving these issues. (shrink)