1. School of Medicine, Johns Hopkins University, Baltimore, MD 21287, USA
2. Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21287, USA
3. Feinberg School of Medicine, Northwestern University, Chicago, IL 60208, USA
4. School of Public Health, University of Minnesota, Minneapolis, MN 55455, USA
5. National Heart, Lung, and Blood Institute, Bethesda, MD 20892, USA
6. School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
7. School of Public Health, University of Alabama at Birmingham, Birmingham, AL 35294, USA
8. Baylor College of Medicine, Houston, TX 77030, USA