[1] Univ Calif Davis, Div Gastroenterol & Hepatol, Davis, CA 95817 USA
[2] Univ Calif Davis, Div Biostat, Dept Publ Hlth Sci, Davis, CA 95817 USA
[3] Univ Calif Davis, Div Rheumatol Allergy & Clin Immunol, Davis, CA 95817 USA
[4] Oslo Univ Hosp, Rikshosp, Norwegian PSC Res Ctr, Clin Specialized Med & Surg, Oslo, Norway
[5] Oslo Univ Hosp, Rikshosp, Inst Immunol, Oslo, Norway
[6] Univ Milan, Ist Clin Humanitas, Ist Ricovero & Cura Carattere Sci, Milan, Italy