[1] Univ Calif San Diego, Dept Pediat, La Jolla, CA USA
[2] Univ Calif San Diego, Dept Pediat, Div Allergy Immunol & Rheumatol, La Jolla, CA 92093 USA
[3] Rady Childrens Hosp, Rady Childrens Fdn, San Diego, CA 92123 USA
[4] Hosp Sick Children, Div Rheumatol, Toronto, ON, Canada
[5] Univ Toronto, Dept Med, Toronto, ON, Canada
[6] Univ Toronto, Dept Pediat, Toronto, ON, Canada