1 Genetics of Complex Traits, Institute of Biomedical and Clinical Science, University of Exeter Medical School, Royal Devon and Exeter Hospital, Exeter EX2 5DW, UK T.M.Frayling@exeter.ac.uk.
2 Genetics of Complex Traits, Institute of Biomedical and Clinical Science, University of Exeter Medical School, Royal Devon and Exeter Hospital, Exeter EX2 5DW, UK European Centre for Environment and Human Health, University of Exeter Medical School, Truro TR1 3HD, UK.