PLA2R1 and membranous glomerulonephritis: Membranous nephropathy, a cause of proteinuria and nephrotic syndrome, is hallmarked by immune deposits containing IgG [predominantly IgG4 antibodies to the phospholipase A2 receptor (PLA2R) in primary MN], autoantigens such as PLA2R, and complement beneath the basal surface of podocytes in the kidney.