1. From the Hypertrophic Cardiomyopathy Center, Minneapolis Heart Institute Foundation (K.M.H., A.G.Z., J.R.L., B.J.M.), Minneapolis, Minn; Hypertrophic Cardiomyopathy Center, Division of Cardiology, Tufts-New England Medical Center (M.S.M., J.E.U.), Boston, Mass; Ente Ospedaliero Ospedali Galliera (P.S., F.F.), Genoa, Italy; Jesse E. Edwards Cardiovascular Registry (S.M.-B.), St. Paul, Minn; and Department of Medicine (Cardiovascular Division), Beth Israel Hospital and Harvard Medical School (W.J.M.),...