• Shane A Bobart, Shahrzad Tehranian, Sanjeev Sethi, Mariam P Alexander, Samih H Nasr, Casal Moura Marta, Julie A Vrana, Samar Said, Callen D Giesen, John C Lieske, Fernando C Fervenza, and An S De Vriese.
• Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN; Cleveland Clinic Florida, Weston.
• Mayo Clin. Proc. 2021 Mar 1; 96 (3): 577-591.

ObjectiveTo describe the clinical and pathological phenotype of membranous nephropathy (MN) associated with M-type-phospholipase-A2-receptor (PLA2R), thrombospondin-type-1-domain-containing-7A (THSD7A), semaphorin 3B (SEMA3B), neural-epidermal-growth-factor-like-1-protein (NELL-1), protocadherin 7 (PCDH7), exostosin 1/exostosin 2 (EXT1/EXT2) and neural cell adhesion molecule 1 (NCAM-1) as target antigens.MethodsA retrospective cohort of 270 adult patients with biopsy-proven MN diagnosed between January 2015 and April 2020 was classified as PLA2R-, THSD7A-, SEMA3B-, NELL-1-, PCDH7-, EXT1/EXT2-, NCAM-1-associated or septuple-negative MN using serologic tests, immunostaining, and/or mass spectrometry. Clinical, biochemical, pathologic, and follow-up data were systematically abstracted from the medical records, including disease activity of conditions traditionally associated with MN and occurring within 5 years of MN diagnosis.ResultsPatients with PLA2R-associated MN were predominantly middle-aged white men without associated disease. The presence of associated disease did not affect the clinical and pathologic characteristics of PLA2R-associated MN, suggesting that they were coincidental rather than causally linked. THSD7A-, NELL-1-, PCDH7-, and NCAM-1-associated MN were rare and SEMA3B-associated MN was not discovered in our cohort. EXT1/EXT2-associated MN was primarily diagnosed in younger women with active systemic autoimmunity. A significant proportion of septuple-negative patients had associated malignancy or systemic autoimmunity.ConclusionThe widely used distinction between primary and secondary MN has limitations. We propose a refined terminology that combines the target antigen and associated disease to better classify MN and guide clinical decision making.Copyright © 2020 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.

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