1. From the Department of Cardiology, Oslo University Hospital, Rikshospitalet and University of Oslo (K.H.H., J.P.A., O.A.S., T.E.), and Institute for Surgical Research (K.H.H., O.A.S., T.E.) and Medical Genetics Laboratory, Department of Medical Genetics (K.E.B., T.P.L.), Oslo University Hospital, Rikshospitalet, Oslo, Norway.