HLA-DRB1 and juvenile idiopathic arthritis: Tyrosine at position 10 (phet = 4.7x10-19, ORfemale = 1.9, ORmale = 1.2), serine at position 11 (phet = 2.3x10-11, ORfemale = 1.9, ORmale = 1.2) and threonine at position 12 (phet = 2.3x10-11, ORfemale = 1.9, ORmale = 1.2), make up the YST motif of DRB1. The effect sizes of the YST motif markers suggest that these markers contribute to JIA onset only in females.