1 Department of Paediatric Endocrinology (M.Z.M.), Royal Manchester Children's Hospital, Manchester, United Kingdom; College of Medicine (T.D.T.), Mayo Clinic, Rochester, Minnesota; Ethel Austin Martin Program (B.L.S.), South Dakota State University, Brookings, South Dakota; Department of Endocrinology and Diabetes (N.J.S., W.H.), Birmingham Children's Hospital, Birmingham, United Kingdom; Vitamin D Research Group (M.K.), School of Food and Nutritional Sciences, and Irish Centre for Fetal and Neonatal Translational Research, University College Cork, Cork, Ireland; Department of Endocrinology and Diabetes (C.F.M.), The Children's Hospital at Westmead, Sydney, Australia; and Institute of Metabolism and Systems Research (W.H.), University of Birmingham, Birmingham, United Kingdom.