At a cut-off of 2.7 RU/ml, selected as the optimal cut-off on the basis of ROC curve analysis, one hundred-five/126 of patients with iMN (83.3%; 95% CI 76.6–89.9) and 18/369 (4.9%; 95% CI 2.8–7.0%) with non-membranous nephropathies were positive for anti-PLA2R antibodies (all but one at a value < 10 RU/ml). The gene discussed is PLA2R1; the disease is membranous glomerulonephritis.