1. From the Departments of Human Genetics (M.V.P.L.R., W-V., B.E.H., M.J., J.S.S., P.P.), Biomathematics (J.S.S.), David Geffen School of Medicine at UCLA, Los Angeles, CA; and Division of Cardiology, McGill University Health Center, Royal Victoria Hospital, Montréal, Canada (I.I., I.R., J.G.).