PLA2R1 and autoimmune disease: Primary membranous nephropathy (MN) is an autoimmune disease caused by circulating antibodies against at least two known membrane proteins, Phospholipase A2 Receptor 1 (PLA2R1) and Thrombospondin Type-l Domain-Containing 7A (THSD7A), which are expressed on human podocytes (1, 2).