LAUSR

Rationale: Focal segmental glomerulosclerosis (FSGS) describes a renal histologic lesion with diverse causes and pathogenicities. Monogenic abnormalities which are associated with impaired function of podocyte could result in FSGS. Most of genetic FSGS do not respond to immunosuppressive agents and often develop end-stage kidney disease. We reported a case of FSGS caused by myosin1e (MYO1E) mutation, alleviated by cyclosporine A (CsA) and low-dose glucocorticoid. Patient concerns: The patient was a 38-year-old male with nephrotic range proteinuria. He didn’t respond to prednisone 65mg/day. Kidney biopsy in our hospital showed FSGS with several hypoplasia and tiny loops. In addition, focal thickening and disorganization of the glomerular gasement membrane as well as diffuse foot process effacement were observed in electron microscope. Diagnoses: Genetic testing indicated homozygous deletion mutation of MYO1E. The patient was diagnosed with genetic FSGS caused by MYO1E homozygous mutation. Interventions: The patient was treated with CsA 50mg twice a day and low-dose methylprednisolone. Outcomes: CsA and low-dose glucocorticoid dramatically reduced proteinuria, and partial remission was attained in 3 years follow-up. Lessons: MYO1E autosomal recessive mutation was a rare FSGS causative mutation that might benefit from CsA treatment. However, the long-term effect of CsA on FSGS caused by this mutation should be investigated in the future.