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M. Sarros, V. Davies, A. Moore, M. Votruba; Four Novel 'Protein Truncating' Mutations in the Dynamin–Central Region of Opa1 Causing Autosomal Dominant Optic Atrophy: Structural Model and Functional Consequences . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4613.
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© ARVO (1962-2015); The Authors (2016-present)
Autosomal dominant optic atrophy (ADOA, OMIM 165500) is the most prevalent hereditary optic neuropathy with an incidence of 1:12,000 to 1:50,000. It is genetically heterogeneous, with three mapped loci: OPA1 on chromosome 3q28–q29, OPA4 on chromosome 18q12.2–q12.3 and OPA5 on chromosome 22q12.1–q13.1. We aimed to explore the mechanism of disease in OPA1 ADOA and to provide insight into the molecular effects of OPA1 mutation by assessing the wider spectrum of disease, addressing the mutation and phenotypic spectrum of the OPA1 gene and modeling the effects on the central–dynamin domain.
Mutation screening by direct sequencing was used to identify mutations in the opa1 gene in a panel of a minimum of 46 patients all clinically diagnosed with ADOA, who had either never been screened before or only partially screened by heteroduplex. Protein modeling studies of the central dynamin region of the OPA1 protein was carried out.
Thirty five sequence changes were identified. There were 15 mutations in OPA1: of which four are novel and 11 are previously reported. In addition, we identified 20 SNPs: of which eight are novel and 12 are reported. The four novel mutations are found in exons 19, 20, 25 and 26, and comprise nucleotide changes c.1824delG, c.1937delC, c.2569C>T, and 2700insTTACAAAT. All four mutations are predicted to be protein truncating and occur in the central dynamin domain (exons 16–26) of OPA1. The mutations occur at highly evolutionarily conserved amino acids. Predictive 3D and homology modeling of the central dynamin of this dynamin–related GTPase, reveals structural similarities to other dynamins across species.
The identification of four novel mutations in the central–dynamin region of OPA1 points towards a significant role for this protein domain. Structural modeling, evolutionary conservation and the protein truncating effects of these mutations provide further proof that haploinsufficiency is likely to be an important mechanism of disease in OPA1 ADOA.
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