Ebstein anomaly and duplication of the distal arm of chromosome 15: report of two patients.

Ebstein anomaly of the tricuspid valve is an uncommon congenital heart defect. We report two unrelated patients with Ebstein anomaly and duplication of the distal long arm of chromosome 15 (15q22 --> qter and 15q24 --> qter). Duplication of 15q is a well-described phenotype that includes congenital heart defects, and these are the first cases with Ebstein anomaly. Duplication of 15q likely affects the early morphogenesis of cardiac structures, including the normal formation of the tricuspid valve.