Fibronectin glomerulopathy caused by genetic FN1 mutation: A case report and literature review

Fibronectin glomerulopathy (FGP), also known as fibronectin deposition glomerulopathy (GFND), is a rare hereditary autosomal dominant glomerular disease. Its clinical manifestations are proteinuria, hematuria, hypertension, and hyperkalemic distal renal tubular acidosis, which often progresses slowly to end-stage renal disease.

We report a 21-year-old woman with fibronectin glomerulopathy who underwent renal puncture at the age of 10. The pathology was considered to be thrombotic microangiopathy, and it was not treated regularly. This time, renal puncture was performed again due to proteinuria combined with elevated serum creatinine. Light microscopy showed severe mesangial matrix hyperplasia of glomeruli with dense deposition and foam cell aggregation in capillary loops. Fibrinogen immunostaining was positive. Electron microscope showed severe hyperplasia of mesangial matrix, and a large amount of electron-dense matter deposited in mesangial area. Perfect genetic testing suggested that the FN1 gene was heterozygous for NM_212482.4 (c.2918A>G), that is, Y973C mutation. Therefore, she was diagnosed with fibronectin glomerulopathy and was given sacubitril valsartan sodium tablets 200 mg b.i.d. orally.

We report a case of a patient with fibronectin glomerulopathy and review the literature of this disease. The disease often has insidious onset, and fibronectin deposition is a typical pathological change that can result. The disease slowly progresses to end-stage renal disease. At present, there is no specific treatment. It is advocated to use reninangiotensin-aldosterone system blockers to strictly control blood pressure and proteinuria, and the overall prognosis is poor. Genetic testing techniques may be helpful in early diagnosis of the disease.