The goal of this study is to elucidate the genetic basis for the congenital heart disease (CHD) known as Ebstein's anomaly. These studies complement ongoing research studies using mouse models to recover mutations causing structural heart defects associated with human CHD. By elucidating the underlying genetic causes for Ebstien's anomaly, it may be possible to improve risk assessments as well as facilitate the development of new strategies for prevention and disease management. These studies are important for early diagnosis and the management of complications associated with surviving adults with Ebstein's anomaly, some of whom have undergone surgical correction and others that are unoperated.