1. Unit on Growth and Obesity (J.C.H.), Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892;
2. Sarah W. Stedman Nutrition and Metabolism Center (M.J.M., H.N.C., C.B.N.), Duke University Medical Center, Durham, North Carolina 27705;
3. Division of Pediatric Endocrinology (A.M.H.), Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada T6G 2J3