Serum autoantibodies used to distinguish primary (idiopathic) membranous nephropathy from secondary causes target an antigen expressed on the foot processes of podocytes. This antigen is:

• A Nephrin of the slit diaphragm
• B THSD7A on endothelial cells
• C The NC1 domain of the alpha-3 chain of type IV collagen
• D M-type phospholipase A2 receptor (PLA2R) ✓

Explanation

Primary membranous nephropathy is an autoimmune disease in which IgG4 antibodies bind the M-type phospholipase D2 receptor on podocytes, forming subepithelial immune deposits in situ. Anti-PLA2R seropositivity supports idiopathic disease, while a negative result should prompt a search for secondary causes such as drugs, hepatitis B, malignancy, and SLE. The alpha-3 NC1 domain is the Goodpasture antigen, and nephrin mutations cause congenital nephrotic syndrome of the Finnish type.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.