#6502 ETIOLOGICAL SPECTRUM OF MEMBRANOUS NEPHROPATHY

Abstract Background and Aims Primary MN includes forms of MN in which there is a humoral autoimmune response to a normal podocyte antigen in the absence of secondary features or etiologies of disease. Antigens implicated in primary MN include PLA2R, thrombospondin type-1 domain-containing 7A (THSD7A), neural epidermal growth factor-like 1 (NELL1), semaphorin 3B (Sema3B), the serine protease high-temperature requirement A1 (HTRA1), protocadherin 7 (PCDH7), and others. PLA2R associated MN is most common MN among primary MN. Nowadays, a significant number of newer antigens implicating MN are being discovered. Research is ongoing for a better understanding of the role of these antigens in pathophysiology, and targeted therapeutic implications in future if possible. We aim to analyze the etiological spectrum associated with different antigens in patients with Membranous Nephropathy. We assessed the renal tissue staining of autoantigens PLA2R, THSD7A, and NELL-1 in patients with biopsy-proven Membranous Nephropathy. Method This was a single center ambispective observational study. The study was performed up till September 2022 for prospective data, and retrospective data from January 2018 to March 2021 was retrieved from the medical records department of the institute. The study included patients with biopsy-proven Membranous Nephropathy (Primary and secondary). The primary outcome was to study the etiological spectrum of Membranous Nephropathy. Results A total of 90 patients were included in the study of membranous nephropathy over the period of 4 years. 72 cases had primary MN whereas 18 cases had secondary MN. The mean age was 42.01 ± 14.6 years. Among 18 cases of Secondary MN, the majority of the cases were of lupus nephritis 14 (78%), while other etiologies of secondary MN were malignancy related (11%), rheumatoid arthritis (5.5%) and HCV (5.5%). PLA2R renal tissue positivity was found in 44 (61.1%) cases of primary MN, whereas in 4 (22.2%) cases of Secondary MN. The THSD7A was found in 4 (5.6%) cases of primary MN. One patient of MN was dual PLA2R and NELL1 positive. Two cases of MN were dual PLA2R and THSD7A positive. Renal tissue staining for NELL-1 was found in 8 (11.1%) cases of primary MN whereas it was found in 1 (5.6%) case of secondary MN. In terms of clinical presentation, proteinuria is the most common clinical finding present in nearly all the patients (80%). Most of the cases with nephrotic syndrome (60%) belonged to primary MN. Conclusion PLA2R is the most common etiology of Primary membranous nephropathy. None of the antigens was exclusive to primary membranous nephropathy.