Fibronectin glomerulopathy in an elderly patient with FN1 gene mutation: a case report and literature review

Fibronectin glomerulopathy (FNG) is a rare autosomal dominant glomerulopathy that can lead to nephrotic syndrome. Here we report the case of an elderly patient diagnosed with FNG, exhibiting nephrotic-range proteinuria, with a 2-year follow-up. A 75-year-old Korean female visited the nephrology clinic after experiencing generalized edema for 2 months. Her serum creatinine was 1.36 mg/dL, and urine protein-to-creatinine ratio was 3.99 g/g. Kidney biopsy revealed mesangial and subendothelial dense deposits, and immunohistochemistry for fibronectin showed strong positivity in the glomerulus. The patient’s family history included non-specific renal disease in her mother and two siblings. Genetic testing of the fibronectin 1 (FN1) gene showed Y973C mutation. She received conservative treatment, including angiotensin II receptor blockers (ARB). Two years after biopsy, the patient has preserved renal function and reduced proteinuria. We report the case of a 75-year-old patient with nephrotic-range proteinuria, who was diagnosed with FNG, and found to harbor a FN1 gene mutation. In this case, conservative treatment including ARB yielded reduction of proteinuria and preservation of renal function.