Abstract: Ｏｂｊｅｃｔｉｖｅ：To investigate the clinical and genetic features of patients with COQ8B nephropathy.
Ｍｅｔｈｏｄｏｌｏｇｙ：We retrospectively analyzed the clinical and pathological manifestations, treatment and prognosis in patients diagnosed with COQ8B nephropathy by genetic test.
Ｒｅｓｕｌｔｓ：A total of nine patients with biallelic mutations of COQ8B were included, among which two patients carried homozygous mutation, and seven patients carried compound heterozygous mutation. The genetic pattern of all patients was consistent with autosomal recessive inheritance pattern. Mutation analysis revealed seven sequence variants in COQ8B (NM_024876 c.748G>C、c.737G>A、c.1093C>G、c.532C>T、c.449G>A、c.1468C>T、c.1465C>T), among which c.737G>A missense mutation is a hotspot mutation in these patients. Patients showed a largely renal-limited phenotype. Of the nine patients, seven started with non-nephrotic proteinuria, and two presented with nephrotic syndrome. The median age at onset was 17 years. Five patients progressed to end-stage kidney disease with a median age at 19 years. Medullary nephrocalcinosis was detected in five patients. Six patients underwent renal biopsy, among which four showed focal segmental glomerulosclerosis. Electron microscopy examination revealed mitochondrial abnormalities. Patients did not respond to immunosuppressive therapy. Treatment with coenzyme Q10 (COQ10) in two patients didnt result in a significant clinical improvement, which may be due to the late initiation of treatment.
Ｃｏｎｃｌｕｓｉｏｎ：COQ8B mutation can lead to autosomal recessive genetic disease manifested by adolescent-onset proteinuria. The main pathological feature is focal segmental glomerulosclerosis. Mitochondrial abnormalities under electron microscope and medullary nephrocalcinosis may be clinical indicators for genetic test. Early genetic diagnosis and COQ10 supplementation can improve prognosis in these patients.

Key words: COQ8B, nephrotic syndrome, focal segmental glomerulosclerosis, medullary nephrocalcinosis