1. Department of Dermatology, Massachusetts General Hospital, Boston, MA 02114, USA.
2. Robert Wood Johnson Medical School, New Brunswick, NJ, USA.
3. Clinical and Translational Epidemiology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
4. Division of Gastroenterology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
5. Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
6. Harvard T.H. Chan School of Public Health, Boston, MA, USA.
7. Department of Dermatology, Massachusetts General Hospital, Boston, MA, USA.