1. Biomolecular Medicine, Division of Surgery, Oncology, Reproductive Medicine and Anaesthetics, Sir Alexander Fleming Building, Imperial College London, SW7 2AZ, U.K., Twin Research and Genetic Epidemiology Unit, Kings College London, U.K., Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Headington, Oxford, OX3 7LJ, U.K., Waters Corporation, 34 Maple Street, Milford, Massachusetts, and Department of Drug Metabolism and Pharmacokinetics, Astra-Zeneca, Macclesfield, U.K.