1. Department of Genetics, University of North Carolina at Chapel Hill , Chapel Hill, NC 27514 , USA
2. Department of Biostatistics, University of North Carolina at Chapel Hill , Chapel Hill, NC 27599 , USA
3. Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill , Chapel Hill, NC 27599 , USA
4. Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont , Burlington, VT 05405 , USA
5. Department of Medicine, University of MS Medical Center (UMMC) , Jackson, MS 39213 , USA
6. Department of Epidemiology, University of Washington , Seattle, WA 98195 , USA
7. Division of Public Health Sciences, Fred Hutchinson Cancer Research , Seattle, WA 98109 , USA