Pregnancy in a Patient With Primary Membranous Nephropathy and Circulating Anti-PLA2R Antibodies: A Case Report

Abstract

There is little information about pregnancy outcomes in patients with active membranous nephropathy (MN), especially those with circulating autoantibodies to M-type phospholipase A₂receptor (PLA₂R), the major autoantigen in primary MN. We present what we believe to be the first known case of successful pregnancy in a 39-year-old woman with PLA₂R-associated MN. In the year prior to pregnancy, the patient developed anasarca, hypoalbuminemia (albumin, 1.3-2.2g/dL), and proteinuria (protein excretion, 29.2 g/d). Kidney biopsy revealed MN with staining for PLA₂R, and the patient was seropositive for anti-PLA₂R autoantibodies. She did not respond to conservative therapy and was treated with intravenous rituximab (2 doses of 1 g each). Several weeks after presentation, she was found to be 6 weeks pregnant and was closely followed up without further immunosuppressive treatment. Proteinuria remained with protein excretion in the 8- to 12-g/d range. Circulating anti-PLA₂R levels declined but were still detectable. At 38 weeks, a healthy baby girl was born, without proteinuria at birth or at her subsequent 6-month postnatal visit. At the time of delivery, the mother still had detectable circulating anti-PLA₂R of immunoglobulin G1 (IgG1), IgG3, and IgG4 subclasses, although at low titers. Only trace amounts of IgG4 anti-PLA₂R were found in cord blood. Potential reasons for the discrepancy between anti-PLA₂R levels in the maternal and fetal circulation are discussed.

Keywords: M-type phospholipase A(2) receptor (PLA(2)R); Membranous nephropathy (MN); autoantibody; immunoglobulin G (Ig G) subclass; nephrotic syndrome; placenta; pregnancy; rituximab.