1. From the Molecular Genetics Section (M.M., A.B., A.S.) and the Laboratory of Neurogenetics (H.D., F.W.D.V., A.S.), National Institute on Aging, National Institutes of Health, Bethesda, Md; the Department of Biostatistical Sciences (W.M.B., L.D.C.), Division of Public Health Sciences, Wake Forest University Medical Center, Winston-Salem, NC; the Department of Neurology (T.G.B., D.G., J.F.M.), Mayo Clinic, Jacksonville, Fla; the Department of Neurology (R.D.B.), Mayo Clinic, Rochester, Minn; the...