University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, UK. Service of Endocrinology, Diabetes and Metabolism, Department of Medicine, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland. University Department of Medical Genetics, Addenbrooke's Hospital, Cambridge, UK. The Alan Turing Institute, London, UK. MRC Biostatistics Unit, University of Cambridge, Robinson Way, Cambridge, UK.