MRC Integrative Epidemiology Unit, School of Social and Community Medicine, Bristol BS8 6BN, UK.|MRC Integrative Epidemiology Unit, School of Social and Community Medicine, Bristol BS8 6BN, UK.|MRC Integrative Epidemiology Unit, School of Social and Community Medicine, Bristol BS8 6BN, UK.|MRC Integrative Epidemiology Unit, School of Social and Community Medicine, Bristol BS8 6BN, UK.|School of Social and Community Medicine, University of Bristol, Bristol BS8 2BN, UK.|School of Social and Community Medicine, University of Bristol, Bristol BS8 2BN, UK.|Dedman College of Humanities and Sciences, Southern Methodist University, Dallas, TX 750235, USA.|Department of Genetics, Environment and Evolution, University College London Genetics Institute, London WC1E 6BT, UK.|Department of Genetics, Environment and Evolution, University College London Genetics Institute, London WC1E 6BT, UK.|Department of Genetics, Environment and Evolution, University College London Genetics Institute, London WC1E 6BT, UK.|School of Social and Community Medicine, University of Bristol, Bristol BS8 2BN, UK.|Department of Genetics, Environment and Evolution, University College London Genetics Institute, London WC1E 6BT, UK.|Department of Genetics, Environment and Evolution, University College London Genetics Institute, London WC1E 6BT, UK.|Department of Genetics, Environment and Evolution, University College London Genetics Institute, London WC1E 6BT, UK.|Department of Genetics, Environment and Evolution, University College London Genetics Institute, London WC1E 6BT, UK.|MRC Integrative Epidemiology Unit, School of Social and Community Medicine, Bristol BS8 6BN, UK.|MRC Integrative Epidemiology Unit, School of Social and Community Medicine, Bristol BS8 6BN, UK.|School of Social and Community Medicine, University of Bristol, Bristol BS8 2BN, UK.