Multiethnic involvement in autosomal-dominant optic atrophy in Singapore.

PurposeAutosomal-dominant optic atrophy (ADOA), often associated with mutations in the OPA1 gene (chromosome 3q28-q29) is rarely reported in Asia. Our aim was to identify and describe this condition in an Asian population in Singapore.Patients and methodsPreliminary cross-sectional study at the Singapore National Eye Centre, including patients with clinical suspicion of ADOA, who subsequently underwent genetic testing by direct sequencing of the OPA1 gene.ResultsAmong 12 patients (10 families) with clinically suspected ADOA, 7 patients (5 families) from 3 different ethnic origins (Chinese, Indian, and Malay) carried a heterozygous pathogenic variant in the OPA1 gene. The OPA1 mutations were located on exons 8, 9, 11, and 17: c.869G>A (p.Arg290Glu), c.892A>G (p.Ser298Gly), c.1140G>A (splicing mutation), and c.1669C>T (p.Arg557*), respectively. One splicing mutation (c.871-1G>A) was identified in intron 8. We also identified a novel mutation causing optic atrophy and deafness (c.892A>G (p.Ser298Gly)). Among the phenotypic features, colour pupillometry disclosed a dissociation between low vision and preserved pupillary light reflex in ADOA.ConclusionWe report the first cases of genetically confirmed OPA1-related ADOA from Singapore, including a novel mutation causing 'ADOA plus' syndrome. Further epidemiological studies are needed in order to determine the prevalence of ADOA in South-East Asia.

A recurrent deletion mutation in OPA1 causes autosomal dominant optic atrophy in a Chinese family.

Autosomal dominant optic atrophy (ADOA) is the most frequent form of hereditary optic neuropathy and occurs due to the degeneration of the retinal ganglion cells. To identify the genetic defect in a family with putative ADOA, we performed capture next generation sequencing (CNGS) to screen known retinal disease genes. However, six exons failed to be sequenced by CNGS in optic atrophy 1 gene (OPA1). Sequencing of those exons identified a 4 bp deletion mutation (c.2983-1_2985del) in OPA1. Furthermore, we sequenced the transcripts of OPA1 from the patient skin fibroblasts and found there is six-nucleotide deletion (c.2984-c.2989, AGAAAG). Quantitative-PCR and Western blotting showed that OPA1 mRNA and its protein expression have no obvious difference between patient skin fibroblast and control. The analysis of protein structure by molecular modeling suggests that the mutation may change the structure of OPA1 by formation of an alpha helix protruding into an existing pocket. Taken together, we identified an OPA1 mutation in a family with ADOA by filling the missing CNGS data. We also showed that this mutation affects the structural intactness of OPA1. It provides molecular insights for clinical genetic diagnosis and treatment of optic atrophy.

A novel OPA1 mutation responsible for autosomal dominant optic atrophy with high frequency hearing loss in a Chinese family.

PURPOSE: To investigate the genetic findings and phenotypic characters of autosomal dominant optic atrophy (ADOA). DESIGN: Case report and experimental study. METHODS: Molecular genetic analysis and clinical examinations were performed in a Chinese family with ADOA. Mutations in OPA1 were detected by direct sequencing. Haplotypes were constructed and compared with the phenotypes in the family. RESULTS: Nine family members were diagnosed with ADOA and some of them were accompanied with hearing loss and/or high myopia. A novel heterozygous mutation, c.2848_2849delGA(p.Asp950CysfsX4), was detected in all ADOA patients. The mutation and the mutation bearing haplotype cosegregated with the nine affected members. One family member had high myopia without vision or hearing loss. This patient along with unaffected ones did not harbor the mutation. CONCLUSIONS: A novel mutation, c.2848_2849delGA in OPA1, was identified in a Chinese family with ADOA. This mutation is associated with hearing loss, but likely not high myopia.

A novel mutation in the OPA1 gene in a Japanese patient with optic atrophy.

PURPOSE: To report a novel mutation of the OPA1 gene in a Japanese patient with optic atrophy and to describe the clinical features of the patient. DESIGN: Observational case report. METHODS: Genomic DNA was extracted from leukocytes of four unrelated Japanese patients with optic atrophy. All the exons and splice sites of the OPA1 gene were amplified by polymerase chain reaction and directly sequenced. RESULTS: One patient with optic atrophy had a heterozygous Arg445His mutation in the OPA1 gene. The Arg445His mutation was detected neither in 110 control subjects nor in the patient's healthy family members. CONCLUSIONS: A novel mutation of the OPA1 gene, similar to those reported in Western countries, was detected in a Japanese patient with optic atrophy. Mutations of the OPA1 gene may contribute to the development of optic nerve atrophy in Japanese cases of optic atrophy.

A novel mutation of the OPA1 gene in a Japanese family with optic atrophy type 1.

PURPOSE: To report a novel mutation of the OPA1 gene in a Japanese family with optic atrophy type 1 (OPA1) and to describe the clinical features of this family. METHODS: Standard ocular examinations were performed on the proband and his two affected sons. The DNA sequence of all exons and splice sites of the OPA1 gene was determined to detect mutations. RESULTS: The proband and his sons had a heterozygous mutation of the OPA1 gene in the third nucleotide of intron 12 (IVS12+3A-->T). Clinically, each patient had reduced visual acuity (onset within the first 6 years of life) and optic nerve pallor. The proband showed bilateral central scotomas and generalized dyschroatopsia. This is the first report of OPA1 gene mutation in Japanese patients with familial optic atrophy. CONCLUSIONS: A mutation of the OPA1 gene was detected in a Japanese family with OPA1, which follows the same pattern as reported in Western countries. It is suggested that mutations of the OPA1 gene contribute to the development of optic nerve atrophy regardless of ethnic groups. Screening for the OPA1 gene mutation will be useful for diagnosis of OPA1 in Japanese patients.