1. From the Nutritional Genetics Unit (G.C.V., C.F.M.) Biomedical Research Institute, National University of Mexico, Mexico City, Mexico 04530
2. Hormone Research Institute (M.S.G., J.W.) University of California San Francisco, San Francisco, California 94143-0534
3. Diabetes Research Center (F.M.M.), University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104-6015