1. From the Departments of Medicine (M.C.C., N.S.K., V.K.D., A.V.K.) and Epidemiology (M.C.C., L.R.L., G.H.), University of North Carolina at Chapel Hill; Department of Neurology, Johns Hopkins University School of Medicine; Baltimore, MD (R.F.G.); and School of Public Health, Human Genetics Center, The University of Texas Health Science Center, Houston (M.L.G.).