OPA1 mutations in Japanese patients suspected to have autosomal dominant optic atrophy

Purpose  

To report three types of heterozygous mutations in the OPA1 gene in five patients from three families with autosomal dominant optic atrophy (ADOA, MIM#165500).     

Optic disc morphology of patients with OPA1 autosomal dominant optic atrophy

BACKGROUND/AIMS: Patients with autosomal dominant optic atrophy (ADOA) are genetically heterogeneous, but all have disc pallor. A degree of cupping in ADOA can make the distinction from normal tension glaucoma (NTG) clinically difficult. This study aimed to clarify the features of the optic nerve of patients with ADOA at the OPA1 locus. METHODS: 29 patients (58 eyes), from 12 families, were identified in a prospective observational study of patients with ADOA examined by a single observer between 1995 and 1998, in whom genetic analysis showed either evidence for linkage to chromosome 3q28 or mutations in the ADOA gene, OPA1. All of the patients had disc and fundal photographs available for retrospective analysis. Clinical data collected included disc appearance, intraocular pressure, Snellen visual acuity, Hardy-Rand-Rittler colour vision plates, and Humphrey 30-2 visual fields. RESULTS: Mean age at time of examination was 37 years and mean visual acuity was 6/24. Disc morphology showed temporal disc pallor in 30 eyes (52%) and total disc pallor in 28 eyes (48%). At least one disc showed a cup to disc ratio of more than 0.5 in 18 patients (28 discs, 48%). The temporal neuroretinal rim always showed pallor and shallow shelving (or saucerisation) was seen in 46 eyes (79%). Only 12 discs (21%) had deep excavation and baring of blood vessels. All of the patients had normal intraocular pressure and no family history of glaucoma. There was a temporal grey, pigmentary crescent in 12 patients (18 eyes, 31%) and peripapillary atrophy in 20 patients (40 eyes, 69%), but disc margin haemorrhages were not seen. There was no maculopathy or retinopathy. CONCLUSION: The optic disc morphology, described for the first time in this genetically homogeneous population of patients with OPA1 ADOA, shows a distinctive absence of a healthy neuroretinal rim and shallow saucerisation of the optic disc cup, with frequent peripapillary atrophy.     

Reduction of inner retinal thickness in patients with autosomal dominant optic atrophy associated with OPA1 mutations

PURPOSE: To determine the morphologic changes in the retina in the macula and around the optic disc in patients with autosomal dominant optic atrophy (ADOA) associated with a mutation in the OPA1 gene. METHODS: Cross-sectional images of the macular area of the retina were obtained by optical coherence tomography (OCT) in patients with ADOA who had a heterozygous mutation in the OPA1 gene. There were 15 eyes of eight patients from five families: four men and four women. The average age of the patients was 48.1 years. In the OCT images, the cross sections of the sensory retina were divided manually into four areas. The thickness of the overall sensory retina and the divided areas were measured at 1 and 2 mm on the temporal, nasal, superior, and inferior sides of the fovea as well as at the fovea. The thickness of the retinal nerve fiber layer (RNFL) around the optic discs was measured by taking circular scans (3.4 mm in diameter) centered on the optic disc. The results in the patients with ADOA were compared with those from 11 normal control subjects. RESULTS: The overall thickness of the sensory retina in the macular area was significantly thinner in the patients with ADOA than in the control subjects at all points except the fovea (P < 0.0001). The RNFL in the macular area in the patients with ADOA was significantly thinner than that in control subjects at all points (P < 0.0001), especially at 1 mm from the fovea. The circumpapillary RNFL was significantly thinner at the temporal, superior, and inferior areas in patients with ADOA but not in the nasal area. The total cross-sectional area of the circumpapillary RNFL was significantly correlated with visual acuity. The thickness of the combined ganglion cell layer, inner plexiform layer, inner nuclear layer, and outer plexiform layer in the macular area was significantly thinner in the patients (P < 0.0056). The thickness of the outer nuclear layer and the photoreceptor inner segments and the thickness of the photoreceptor outer segments were not significantly different between the patients with ADOA and normal control subjects. CONCLUSIONS: The RNFL and the layer including the ganglion cell layer are significantly thinner in patients with ADOA associated with an OPA1 gene mutation, whereas the photoreceptor layers are not affected morphologically. The inner retina is the main area of the retina altered in ADOA.     

Reduction of oscillatory potentials and photopic negative response in patients with autosomal dominant optic atrophy with OPA1 mutations

PURPOSE: To study the electroretinographic (ERG) findings in patients with autosomal dominant optic atrophy (ADOA) with OPA1 mutations. METHODS: Eight ADOA patients (age range, 24-55 years; mean, 41 years) with OPA1 mutations were studied. In addition to routine ophthalmological tests, full-field ERGs including the rod response, mixed rod-cone response, oscillatory potentials (OPs), single-flash cone response, and photopic negative response (PhNR) were recorded and compared with those from 25 age-matched controls. The correlation between the ERG data and averaged retinal nerve fiber layer (RNFL) thickness around the optic disk measured by optical coherent tomography, mean deviation of the static perimetry (Humphrey 30-2 program), or corrected visual acuity was also examined. RESULTS: Amplitudes of the PhNR and OPs, both of which are believed to originate from inner retinal layers, were significantly smaller in ADOA patients than in control subjects (P < 0.01). Amplitudes of other ERG components were not statistically different in the two groups. OP amplitude was inversely correlated with the patient's age. The RNFL was thinner and the retinal sensitivities obtained by static perimetry were lower in ADOA patients, but these values were not correlated with the amplitude of PhNR or OPs. CONCLUSIONS: These results suggested that there are functional impairments not only in the ganglion cell layer but also in the inner nuclear and plexiform layers, including the amacrine cells of ADOA patients with OPA1 mutations.     

Autosomal dominant optic atrophy: penetrance and expressivity in patients with OPA1 mutations

PURPOSE: We identified families with autosomal dominant optic atrophy (ADOA), determined the number and type of OPA1 mutations, and investigated the phenotypic variation and penetrance in ADOA Australian pedigrees. DESIGN: Cross-sectional genetics study. METHODS: Probands were identified on the basis of characteristic clinical features of ADOA. We screened the OPA1 gene using single-strand conformational polymorphism, heteroduplex analysis (SSCP/HA), or by direct sequencing. Penetrance for pedigrees in which a mutation of OPA1 had been identified was calculated initially using all recruited individuals, and subanalysis was performed using only those families for which there was total recruitment of siblings. RESULTS: A total of 406 patients from 17 pedigrees were recruited, and OPA1 mutations were identified in 11/17 (65%) of these. The mean age at clinical examination was 38.2 +/- 19.9 years (median age, 35 years; range, four to 83 years). The median best-corrected visual acuity in OPA1-mutation carriers was 20/70 (range, 20/16 to hand movements [HM]). The penetrance in Australian ADOA pedigrees in the families with complete sibling recruitment was 82.5%. On the other hand, overall penetrance for all individuals harboring an OPA1 mutation was 88%. CONCLUSIONS: OPA1 mutations were identified in 11/17 (65%) of the ADOA pedigrees in this study. The penetrance in our cohort was lower than originally described (82.5% vs 98%) but higher than some recent studies since the availability of genotyping. It is anticipated that this figure would be even lower as more asymptomatic individuals are identified. There are likely to be other genetic and environmental modifiers influencing disease penetrance.     

A novel mutation of the OPA1 gene responsible for isolated autosomal dominant optic atrophy in two brothers

Autosomal dominant optic atrophy, or Kjer disease, is the most frequent form of autosomal dominant optic neuropathy. We report a novel mutation of the OPA1 gene in two brothers with autosomal dominant optic atrophy and describe their clinical features. The two patients, aged 41 and 37, presented with a bilateral visual impairment that had been detected at the age of 4 in both of them. Their ophthalmoscopic examinations disclosed a bilateral optic atrophy and their Goldmann visual fields showed cecocentral scotomas. The patients thought their disease might be a Leber's hereditary optic neuropathy; however, mutations had ever been sought. When first seen by us, they wished to know whether their disorder might be transmitted to their children. They had a family history of visual impairment. We carried out mtDNA sequencing but we did not identify any primary or rare Leber's hereditary optic neuropathy mutations. On the other hand, the 30 coding exons of the OPA1 gene and the intron-exon junctions were amplified by polymerase chain reaction and sequenced. A novel mutation of the OPA1 gene was found in both brothers: a deletion of four nucleotides in intron 19, associated with anomalous splicing, demonstrating the pathogenicity of the mutation. These molecular analyses contributed to identifying a novel mutation of the OPA1 gene with a clinical phenotype of isolated optic atrophy.     

Pattern of retinal ganglion cell loss in dominant optic atrophy due to OPA1 mutations

Purpose

The majority of patients with autosomal dominant optic atrophy (DOA) harbour pathogenic OPA1mutations. Although DOA is characterised by the preferential loss of retinal ganglion cells (RGCs), about 20% of patients with OPA1mutations will develop a more severe disease variant (DOA+), with additional neuromuscular features. In this prospective, observational case series, optical coherence tomography (OCT) was used to define the pattern of retinal nerve fibre layer (RNFL) loss in patients with both the pure and syndromal forms of DOA.

Methods

Forty patients with a molecular diagnosis of DOA due to OPA1mutations were prospectively recruited from our neuro-ophthalmology clinic: 26 patients with isolated optic atrophy and 14 patients manifesting DOA+ features. Peripapillary RNFL thickness was measured with the Fast RNFL (3.4) acquisition protocol on a Stratus OCT.

Results

There was a statistically significant reduction in average RNFL thickness in the OPA1group compared with normal controls (P<0.0001). The percentage decrease was greatest in the temporal quadrant (59.0%), followed by the inferior (49.6%), superior (41.8%), and nasal (25.9%) quadrants. Patients with DOA+ features had worse visual outcomes compared with patients with pure DOA. Except in the temporal quadrant, RNFL measurements were significantly thinner for the DOA+ group. There was an inverse correlation between average RNFL thickness and logarithm of the minimum angle of resolution (LogMAR) visual acuity (P<0.0001).

Conclusions

RGC loss in DOA is characterised by severe involvement of the temporal papillomacular bundle, with relative sparing of the nasal fibres. RNFL thinning is more pronounced in patients with DOA+ phenotypes.     

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.     

常染色体显性视神经萎缩研究进展

常染色体显性视神经萎缩（ADOA）,又称为Kjer型视神经萎缩,是显性遗传性视神经疾病中最常见的一种,其发病率为1：10000～1：50000。其主要的临床表现为视力下降、色觉障碍、视野缺损等,特征性的眼底改变为颞侧视盘苍白。本病还可以伴随听力下降、白内障、眼外肌麻痹、上睑下垂等。目前,已发现的ADOA候选基因位点包括OPA1（3q28—29）、OPA3（19q13．2—13．3）、OPA4（18q12．2—12．3）和OPA5（22q12．1—13．1）等。其中,OPA1与OPA3位点均已克隆出相应的同名基因,但本病的基因型与表型的关系及致病机制还不十分明确。就ADOA的临床表现、与ADOA相关的侯选基因、位点及其鉴别诊断的最新研究进行总结。     

OPA1, the disease gene for autosomal dominant optic atrophy, is specifically expressed in ganglion cells and intrinsic neurons of the retina

PURPOSE: Autosomal dominant optic atrophy is a hereditary disorder characterized by progressive loss of vision and caused by mutations in a dynamin-related gene, OPA1, which translates into a protein with a mitochondrial leader sequence. In this study the OPA1 gene and its protein were localized in the rat and mouse retina, and its rat orthologue, rOpa1, was identified. METHODS: The rOpa1 cDNA was isolated by using reverse transcribed cDNA from total RNA obtained from a rat retinal ganglion cell line. The spatial and temporal expression patterns of OPA1 and its gene product were investigated by RNA in situ hybridization and immunohistochemistry in mouse and rat retinas. To characterize further the OPA1-positive neurons, retinal ganglion cells were retrogradely labeled by an immunogold fluorescent tracer or double labeled with OPA1 and choline acetyltransferase or calbindin antibodies. RESULTS: Protein sequence alignment revealed a 96% identity between rat and human OPA1 mRNA. OPA1 expression was found as early as postnatal day 3 in the developing rodent retina. In the mature retina, the OPA1 gene and its protein were found not only in retinal ganglion cells, but also in starburst amacrine cells and horizontal cells, both of which are involved in lateral signal processing within the retina. However, OPA1 was absent from mitochondria rich nerve fibers and photoreceptor indicating a specific role for OPA1 in signal processing rather than in the requirement of mitochondrial energy supply in the retina. CONCLUSIONS: The data suggest an important and specific function of the OPA1 protein, not only in the optic nerve forming ganglion cells but also in the intrinsic signal processing of the inner retina.     

The association of autosomal dominant optic atrophy and moderate deafness may be due to the R445H mutation in the OPA1 gene

PURPOSE: To examine the involvement of the optic atrophy 1 (OPA1) gene in optic atrophy associated with moderate deafness. DESIGN: Observational case report.The entire coding sequence of the OPA1 gene was directly sequenced in the case of a patient suffering from optic atrophy associated with moderate deafness. RESULTS: A de novo heterozygous mutation R445H in the OPA1 gene was found. No similar mutation was detected in either of the patient's parents or in the 100 chromosome controls. CONCLUSION: The R445H mutation in OPA1 might be the cause of the association between dominant optic atrophy and moderate deafness, a phenotype that may be currently underdiagnosed.     

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

PURPOSE: To report a novel mutation of the type1 optic atrophy(OPA1) gene in a Japanese family with 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 a central scotoma and generalized dyschromatopsia. 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.     

A clinicopathologic study of autosomal dominant optic atrophy.

Of a family with 40 members, 12 had autosomal dominant optic atrophy. The affected members were aware of reduced vision from the first decade. Visual loss was moderate to severe, 6/12 (20/40) to 3/60 (10/200). The affected members showed similar centrocecal scotomata. Most affected patients had severe unclassified color defects. Electroretinography measurements were normal in all but one patient who had a small reduction in the scotopic response. The pathologic changes in a patient with autosomal dominant optic atrophy showed diffuse atrophy of the ganglion cell layer of the retina with a loss of myelin and nerve tissue within the optic nerves. We suggest that autosomal dominant atrophy is a primary degeneration of retinal ganglion cells.     

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.