1. From the Department of Medicine, Genetics Program (R.S.), Boston University School of Medicine, Boston, MA; School of Public Health (C.E.F., B.R.D., E.B.), University of Texas, Houston, TX; Department of Laboratory Medicine and Pathology (J.H.E.), University of Minnesota, Minneapolis, MN; and Department of Epidemiology (D.K.A.), University of Alabama, Birmingham, AL.