[1] Univ Penn, Div Rheumatol, Rheumatol, Philadelphia, PA 19104 USA
[2] Univ Penn, Rheumatol, Philadelphia, PA 19104 USA
[3] NIAMSD, NIH, Bethesda, MD 20892 USA
[4] Univ Penn, Childrens Hosp Philadelphia, Gastroenterol Hepatol & Nutr, Philadelphia, PA 19104 USA
[5] Univ Penn, Philadelphia, PA 19104 USA
[6] Univ Penn, Div Rheumatol, Philadelphia, PA 19104 USA