A Rare Case Report of Fanconi Anemia-Associated Nuclease 1 Mutation Causing Nephrotic Syndrome.

A 25-year-old African male patient presented with a history of frothy urination for one month. He had a significant family history of early onset chronic kidney disease (CKD) in his older brother. On evaluation, he was found to have deranged renal function and nephrotic-range proteinuria of 6152 mg/day. Urine examination revealed proteinuria and glycosuria. Viral serology and autoimmune screening results were negative. Ultrasonography revealed contracted kidneys that were not amenable to biopsy. Genetic analysis revealed a Fanconi anemia-associated nuclease 1 (FAN 1) mutation in exon 4 (c.1399G>A) and exon 12 (c.2786A>C). The patient was managed conservatively with a maximum dose of angiotensin receptor blockers with a reduction in proteinuria on follow-up. This case report highlights the rare manifestation of FAN 1 mutation and its variable effects on the kidney.