The OPA1 Gene Mutations Are Frequent in Han Chinese Patients with Suspected Optic Neuropathy

Abstract

While many patients with hereditary optic neuropathies are caused by mitochondrial DNA (mtDNA) mutations of Leber's hereditary optic neuropathy (LHON), a significant proportion of them does not have mtDNA mutation and is caused by mutations in genes of the nuclear genome. In this study, we investigated whether the OPA1 gene, which is a pathogenic gene for autosomal dominant optic atrophy (ADOA), is frequently mutated in these patients. We sequenced all 29 exons of the OPA1 gene in 105 Han Chinese patients with suspected LHON. mtDNA copy number was quantified in blood samples from patients with and without OPA1 mutation and compared to healthy controls. In silico program-affiliated prediction, evolutionary conservation analysis, and in vitro cellular assays were performed to show the potential pathogenicity of the mutations. We identified nine OPA1 mutations in eight patients; six of them are located in exons and three are located in splicing sites. Mutation c.1172T > G has not been reported before. When we combined our data with 193 reported Han Chinese patients with optic neuropathy and compared to the available data of 4327 East Asians by the Exome Aggregation Consortium (ExAC), we found a significant enrichment of potentially pathogenic OPA1 mutations in Chinese patients. Cellular assays for OPA1 mutants c.869G > A and c.2708_2711del showed abnormalities in OPA1 isoforms, mitochondrial morphology, and cellular reactive oxygen species (ROS) level. Our results indicated that screening OPA1 mutation is needed for clinical diagnosis of patients with suspected optic neuropathy.

Keywords: Han Chinese; Mitochondrial dysfunction; OPA1; Pathogenicity; Suspected optic neuropathy.