1. From the Locus for Homocysteine and Related Vitamins, University of Bergen, Norway (P.I.H., P.M.U., S.E.V., Ø.M), the Hormone Laboratory (P.I.H.) and the Laboratory of Clinical Biochemistry (P.M.U.), Haukeland University Hospital, and the Laboratory of Pediatrics and Neurology (H.J.B.) and the Department of Endocrinology (M.B.A.J.K., M.d.H.), University Medical Center Nijmegen, The Netherlands.