IgA nephropathy, though sharing clinical features like proteinuria and hematuria (29), demonstrates distinct pathological characteristics with predominant mesangial IgA deposition on immunofluorescence staining (14), contrasting with the linear IgG pattern of anti-GBM nephritis and featuring cutaneous purpura in HSPN (16). The gene discussed is CD79A; the disease is IgA glomerulonephritis.