CD79A and polyarticular juvenile idiopathic arthritis: When patients affected by JIA were stratified for joint involvement and severity of the disease (polyarticular, pauciarticular, and systemic JIA) a significant difference was observed for AAE IgA titre in polyarticular JIA versus HC (P = 2.0exp−4) and poliarticular JIA versus systemic JIA (P = 0.004); for AAE IgG all the subgroups were significantly different compared to HC (Table 3).