The highest AUROC of the IgA/C3 ratio for an IgAN diagnosis was in the proteinuria≤1 g/d group (0.801 in the full cohort, and 0.803 in the PSM cohort); however, there was no difference in the AUROC of the IgA/C3 ratio between all CKD groups. The gene discussed is C3; the disease is chronic kidney disease.