<p>Fibronectin glomerulopathy (FNG) is a rare autosomal dominant inherited disease characterized by extensive deposits of fibronectin in the mesangium and subendothelial space of the glomeruli with membranoproliferative glomerulonephritis (MPGN)-like pattern. Currently, ten exonic and one intronic pathogenic variants in the fibronectin 1 gene have been identified; however, genotype–phenotype correlation data are lacking. We herein report a familial FNG caused by a splice site variant in intron 36 (c.5888-2A &gt; G). The gene mutation was recently found, but to our knowledge, this is the first case report of a familial FNG with the intronic variant that describes the clinicopathological characteristics. In the current study, Case 1 is a previously healthy 29-year-old woman with nephrotic syndrome. Treatment with glucocorticoids, combined with the immunosuppressant mizoribine and an angiotensin II receptor blocker (ARB), resulted in an incomplete remission of nephrotic syndrome; however, renal function has been preserved. Case 2, the mother of Case 1, is a 49-year-old woman with vasculo-Behçet’s disease with mild proteinuria and renal dysfunction. Due to the administration of azathioprine, aspirin, and ARB, renal function and proteinuria have been stable over 10&#xa0;years. The kidney biopsy revealed MPGN-like histological features in both the mother and the daughter; however, the mesangial area exhibited a milder expansion in the mother than in the daughter. Accumulating genotype–phenotype correlation data will be essential for managing FNG.</p>