Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA.|Department of Statistics.|Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.|Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA.|Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA.|Department of Cellular and Molecular Medicine, Institute of Genomic Medicine, UCSD Moores Cancer Center, University of California, San Diego School of Medicine, La Jolla, CA 92093, USA.|Department of Quantitative Health Sciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.|Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA.