1. From the Divisions of Cardiology (A.I.F., A.J.L.) and Medical Genetics (L.S.R.), Department of Medicine, Department of Microbiology and Molecular Genetics (A.J.L.), Molecular Biology Institute, UCLA, Los Angeles, Calif; the University of Kentucky College of Medicine (F.C.D.), Lexington, Ky; and the Division of Medical Genetics (R.M.C., J.I.R.), Departments of Medicine and Pediatrics, Cedars-Sinai Research Institute, Los Angeles, Calif.