1. Whitehead/MIT Center for Genome Research, Cambridge, MA 02139, USA.
2. Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
3. National Human Genome Center, Howard University, Washington, DC 20059, USA.
4. Department of Pediatrics, College of Medicine, University of Ibadan, Ibadan, Nigeria.
5. Department of Preventive Medicine and Epidemiology, Loyola University Medical School, Maywood, IL 60143, USA.
6. Institute of Biological Anthropology, University of Oxford, Oxford, England OX2 6QS.
7. Departments of Genetics and Medicine, Harvard Medical School; Department of Molecular Biology and Diabetes Unit, Massachusetts General Hospital, Boston, MA 02114, USA.