1. Department of Twin Research and Genetic Epidemiology, King’s College London, London, UK
2. Division of Rheumatology, Orthopaedics and Dermatology, School of Medicine, University of Nottingham, Nottingham, UK
3. Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK
4. NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Nottingham, UK