Role of DNA testing for diagnosis, management, and genetic screening in long QT syndrome, hypertrophic cardiomyopathy, and Marfan syndrome.

In recent years the molecular genetics and pathophysiology of long QT syndrome (LQTS), hypertrophic cardiomyopathy (HCM), and Marfan syndrome have been extensively studied. Each disease shows highly variable expression and reduced penetrance of all known phenotypic manifestations and the diagnosis is often diYcult. In addition, the possibility of genotype specific treatment has been raised for LQTS. As a consequence of these diagnostic and therapeutic issues, the role of DNA analysis (genotyping) has become a topic of substantial interest. Further, as each of these diseases causes unexpected sudden death in children and young adults, often during physical activity, the role of athletic preparticipation screening, including DNA testing, is now a widely discussed topic. This editorial will, therefore, examine the role of genotyping for: (1) diagnosis and management of individual patients; and (2) for “genetic screening”, the identification of these diseases in populations such as young athletes.