CD79A and nephritis: Urinary IgA was acceptable at distinguishing patients with IgAV from HC (AUC 0.707, 95% CI [0.564–0.851], p = 0.028) and excellent at discriminating patients with and without nephritis (IgA—AUC 0.838, 95% CI [0.704–0.973], p < 0.001).