Case report: dual pathology of LMX1B-associated nephropathy and iga nephropathy in a middle-aged woman

BACKGROUND: Proteinuria is a common manifestation of glomerular disease. Advances in genetic testing have improved recognition of hereditary nephropathies such as LMX1B-associated nephropathy. Coexistence with immune-mediated glomerulonephritis is exceptionally rare. CASE REPORT: We describe a 58-year-old woman with a history of hypertension, type 2 diabetes mellitus, hyperlipidemia, and prior pulmonary embolism who presented with persistent proteinuria. Urinary protein-to-creatinine ratios ranged from 1679 to 3944 mg/g, while renal function remained preserved (estimated GFR 69-103 mL/min/1.73 m²). Genetic testing identified a pathogenic LMX1B mutation consistent with nail-patella syndrome, along with variants of uncertain significance in CYP11B1, ABCC8, and PLG. Kidney biopsy revealed IgA nephropathy with mesangial IgA deposition and ultrastructural findings of podocyte myelinosomes, characteristic of LMX1B-associated nephropathy. Chronicity was minimal (3 of 23 glomeruli globally sclerotic, no segmental sclerosis, and no interstitial fibrosis). Management included renin-angiotensin system blockade and metabolic optimization. CONCLUSION: This case illustrates the diagnostic complexity of dual glomerular pathology and underscores the importance of integrating genetic testing with histopathology in patients with atypical proteinuria.