1. Departments of Pediatrics (M.J.J.F., F.J.W., J.M.W.), Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
2. Clinical Epidemiology (M.J.J.F., F.W.D.), Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
3. Department of Pediatrics (M.J.J.F.), VU University Medical Center, 1007 MB Amsterdam, The Netherlands
4. Molecular Epidemiology (I.M., P.E.S.), Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
5. Clinical Chemistry (M.F.), Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
6. Endocrinology and Metabolic Diseases (J.A.R.), Leiden University Medical Center, 2333 ZA Leiden, The Netherlands