Pillebout and colleagues were the first to report increased urinary IgA concentrations in children with IgAVN, and they also found that the urinary IgA/Cr performed very well at identifying patients with nephritis (AUC 0.86; 95% CI [0.75–0.96]; p < 0.0001), with area under the curve values aligned with our findings. Here, CD79A is linked to nephritis.