Abstract: FR-PO0694
From Flank Pain to Graft-vs.-Host Disease-Related Autoimmune Podocytopathy: A Case of FAT1+ Membranous Nephropathy
Session Information
- Glomerular Diseases: Membranous Nephropathy, FSGS, and Podocytopathies
October 23, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Moustafa, Amr, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
- Moudgalya, Hita S., The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
- Ayoub, Isabelle, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
- Dasgupta, Alana, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
- Chung, Madeline S., The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
- Kang, Rima, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
Introduction
Membranous nephropathy (MN) is a known complication of chronic graft versus host disease (GVHD) following hematopoietic stem cell transplantation (HSCT). Protocadherin FAT1 has been identified as one of the target antigens mediating HSCT-induced MN (1). We present the case of a 37-year-old man with a history of relapsed Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) who developed FAT1+ MN after allogeneic HSCT.
Case Description
Our patient underwent an allogeneic HSCT in November 2023 which was complicated by multiorgan chronic GVHD for which he was started on ruxolitinib and belumosudil. He subsequently presented to the hospital with right flank pain and was found to have a renal infarction, prompting nephrology consultation. Work up revealed microscopic hematuria, nephrotic-range proteinuria (uPCR 17.6 g/g), severe hypoalbuminemia (1.8 g/dL) but no peripheral edema and a mildly elevated serum creatinine of 0.89. Infectious and serological workups were unrevealing.
Kidney biopsy showed IgG1/IgG4 codominant membranous nephropathy negative for PLA2R and NELL1. The tissue was sent for mass spectrometry which identified Protocadherin FAT1 on LC-MS/MS, confirming FAT1-mediated MN secondary to HSCT.
Discussion
In addition to anticoagulation, the patient was started on a calcineurin inhibitor with plans for outpatient B-cell depletion therapy. Recent studies show FAT1 serves as the autoantigen in HSCT-associated MN (1,2). Pathophysiology likely involves HSCT -conditioning-related aberrant FAT1 expression in podocytes and dysregulated immune reconstitution with excess BAFF promoting autoreactive B cell clones and pathogenic autoantibodies such as anti-FAT1 antibodies (2). While LC-MS/MS identified the antigen target in this case, cohort data show that FAT1+MN can also be identified by immunofluorescence. In FAT1+ MN, IgG subtyping may vary, with IgG4 dominance ranging from the majority of cases to as low as 30%.