1. Intramural Research Support Program, Science Applications International Corporation Frederick, National Cancer Institute (NCI), Frederick, MD 21702–1201, USA.
2. The Johns Hopkins School of Hygiene and Public Health, Baltimore, MD 21205, USA, for AIDS Linked to Intravenous Experience Cohort.
3. Viral Epidemiology Branch, NCI–Executive Plaza North, Bethesda, MD 20892, USA, for Multicenter Hemophilia Cohort Study.
4. University of Alabama, Birmingham, AL 35294, USA, for Multicenter AIDS Cohort Study.
5. San Francisco City Clinic Cohort, San Francisco, CA 94102, USA, for San Francisco City Cohort.
6. Gulf States Hemophilia Center, University of Texas Health Science Center, Houston, TX 77030, USA, for the Hemophilia Growth and Development Study.
7. Laboratory of Genomic Diversity, NCI, Frederick, MD 21702, USA.