Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA.|College of Public Service, Jackson State University, Jackson Heart Study, Jackson, MS 39213, USA.|Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA.|Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS 39216, USA and.|Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA.|Department of Epidemiology, University of Texas Health Science Center, Houston, TX 77225, USA.