1. From Departments of Internal Medicine, Pediatrics, and Molecular Pharmacology & Experimental Therapeutics; Divisions of Cardiovascular Diseases and Pediatric Cardiology; Windland Smith Rice Sudden Death Genomics Laboratory; Mayo Clinic, Rochester, MN (M.A.);Stead Family Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa, City (D.L.A.); andDepartment of Cardiology, Boston Children’s Hospital, MA (J.K.T.).