Progressive Optic Atrophy Research Articles

Progressive autosomal dominant optic atrophy and sensorineural hearing loss in a Turkish family

Purpose: To describe the clinical features, mode of inheritance, and linkage analysis of ten affected members of a three-generation family with progressive optic atrophy and progressive hearing loss. Materials and methods: The proband, a 10-year-old boy, presented with progressive visual failure. Ten other members in his family, including his mother, half-sister, aunt, two uncles, grandfather, and some of the cousins, also had progressive visual loss and hearing loss. Six affected and four unaffected cases were examined in detail. Blood samples were drawn from 16 members for DNA extraction. Two loci previously described for optic atrophy were tested for linkage in the present family. Results: The mode of inheritance was clearly autosomal dominant. Six members of the family were found to have progressive optic atrophy and hearing loss, both starting in the first decade of life. Total or red-green color blindness was detected in some patients. None of the members of this family showed evidence of other systemic disorders; however, four had blepharochalasis. No other cause could be found for the hearing or the visual loss. Linkage analysis excluded OPA1 and OPA2. Conclusion: The present Turkish family belongs to the group of individuals with autosomal dominantly inherited optic atrophies with hearing loss. Linkage analysis excluded OPA1 and OPA2, indicating that a novel gene defect underlies the disease in this family. Further genome-wide linkage analysis and identification of the disease-associated gene will help define the pathophysiology of this syndrome.

Temporal Bone Histopathologic and Genetic Studies in Mohr-Tranebj??rg Syndrome (DFN-1)

To describe the temporal bone histopathologic and genetic abnormalities in a case of Mohr-Tranebjaerg syndrome. Mohr-Tranebjaezrg syndrome (DFN-1) is an X-linked, recessive, syndromic hearing loss, characterized by postlingual sensorineural hearing loss with onset in childhood, followed in adult life by progressive dystonia, spasticity, dysphagia, and optic atrophy. The syndrome is caused by mutations in the DDP (deafness/dystonia peptide) gene, which are thought to result in mitochondrial dysfunction with subsequent neurodegeneration. The temporal bone pathologic changes in this syndrome have not been reported. Hearing loss developed in the patient at age 4, blindness at age 48, and dystonia at age 57. Genetic studies on peripheral blood showed a l51delT mutation in his DDP gene. He died at age 66. The right temporal bone was subjected to light microscopy and polymerase chain reaction-based analysis of the DDP gene sequence. There was near complete loss of spiral ganglion cells with loss of nearly all peripheral and central processes. Only 1,765 spiral ganglion cells remained (8.5% of mean normal for age). The organ of Corti (including hair cells), stria vascularis, and spiral ligament were preserved. There was also a severe loss of Scarpa's ganglion cells with preservation of vestibular hair cells. The population of geniculate and trigeminal ganglion cells appeared normal. Sequence analysis from temporal bone DNA showed the 15ldelT DDP gene mutation. Sensorineural hearing loss in Mohr-Tranebjaerg syndrome is the result of a postnatal, progressive, severe auditory neuropathy.

WFS1 (Wolfram syndrome 1) gene product: predominant subcellular localization to endoplasmic reticulum in cultured cells and neuronal expression in rat brain.

Wolfram (DIDMOAD) syndrome is an autosomal recessive neurodegenerative disorder accompanied by insulin-dependent diabetes mellitus and progressive optic atrophy. Recent positional cloning led to identification of the WFS1 (Wolfram syndrome 1) gene, a member of a novel gene family of unknown function. In this study, we generated a specific antibody against the C-terminus of the WFS1 protein and investigated its subcellular localization in cultured cells. We also studied its distribution in the rat brain. Biochemical studies indicated the WFS1 protein to be an integral, endoglycosidase H-sensitive membrane glycoprotein that localizes primarily in the endoplasmic reticulum (ER). Consistent with this, immunofluorescence cell staining of overexpressed WFS1 showed a characteristic reticular pattern over the cytoplasm and overlapped with the ER marker staining. No co-localization of WFS1 with mitochondria argues against an earlier clinical hypothesis that Wolfram syndrome is a mitochondria-mediated disorder. In the rat brain, at both the protein and mRNA level, WFS1 was found to be present predominantly in selected neurons in the hippocampus CA1, amygdaloid areas, olfactory tubercle and superficial layer of the allocortex. These expression sites, i.e. components of the limbic system or structures closely associated with this system, may be involved in the psychiatric, behavioral and emotional abnormalities characteristic of this syndrome. ER localization of WFS1 suggests that this protein plays an as yet undefined role in membrane trafficking, protein processing and/or regulation of ER calcium homeostasis. These studies represent a first step toward the characterization of WFS1 protein, which presumably functions to maintain certain populations of neuronal and endocrine cells.

WFS1/wolframin mutations, Wolfram syndrome, and associated diseases.

Wolfram syndrome (WS) is the inherited association of juvenile-onset insulin-dependant diabetes mellitus and progressive bilateral optic atrophy. A nuclear gene, WFS1/wolframin, was identified that segregated with disease status and demonstrated an autosomal recessive mode of inheritance. Mutation analysis of the WFS1 gene in WS patients has identified mutations in 90% of patients. Most were compound heterozygotes with private mutations distributed throughout the gene with no obvious hotspots. The private nature of the mutations in WS patients and the low frequencies make it difficult to determine the biological or clinical relevance of these mutations. Mutation screening in patients with psychiatric disorders or diabetes mellitus has also been performed to test the hypothesis that heterozygous carriers of WFS1 gene mutations are at an increased risk following the observation that WS first-degree relatives have a higher frequency of these disorders. Most studies showed no association, however two missense mutations were identified that demonstrated significant association with psychiatric disorders and diabetes mellitus. Population association studies and functional studies of these variants will need to be performed to confirm these preliminary results. The elucidation of functions and functional pathways for the WFS1 gene product and variants will shed light on the effect of such disparate mutations on gene function and their role in the resulting clinical phenotype in WS and associated disorders.

Late-onset optic atrophy, ataxia, and myopathy associated with a mutation of a complex II gene

Genetic defects affecting the mitochondrial respiratory chain are an important cause of neurological disease. Previously, we identified a family with complex II deficiency and late-onset neurodegenerative disease with progressive optic atrophy, ataxia, and myopathy. The affected family members are now shown to carry a C-to-T transition in one allele of the nuclear gene encoding the flavoprotein subunit of complex II. Mutation of the equivalent base in Escherichia coli generates an inactive enzyme unable to bind flavin adenine dinucleotide covalently. Compatible with these findings, our patients have an approximate 50% decrease in complex II and succinate dehydrogenase activity. These results suggest that genetic defects of nuclear-encoded subunits of the mitochondrial respiratory chain can result in late-onset neurodegenerative disease.

Hereditary Ataxias

Hereditary Ataxias

Clinical and Molecular Genetic Analysis of 19 Wolfram Syndrome Kindreds Demonstrating a Wide Spectrum of Mutations in WFS1

Wolfram syndrome is an autosomal recessive neurodegenerative disorder characterized by juvenile-onset diabetes mellitus and progressive optic atrophy. mtDNA deletions have been described, and a gene (WFS1) recently has been identified, on chromosome 4p16, encoding a predicted 890 amino acid transmembrane protein. Direct DNA sequencing was done to screen the entire coding region of the WFS1 gene in 30 patients from 19 British kindreds with Wolfram syndrome. DNA was also screened for structural rearrangements (deletions and duplications) and point mutations in mtDNA. No pathogenic mtDNA mutations were found in our cohort. We identified 24 mutations in the WFS1 gene: 8 nonsense mutations, 8 missense mutations, 3 in-frame deletions, 1 in-frame insertion, and 4 frameshift mutations. Of these, 23 were novel mutations, and most occurred in exon 8. The majority of patients were compound heterozygotes for two mutations, and there was no common founder mutation. The data were also analyzed for genotype-phenotype relationships. Although some interesting cases were noted, consideration of the small sample size and frequency of each mutation indicated no clear-cut correlations between any of the observed mutations and disease severity. There were no obvious mutation hot spots or clusters. Hence, molecular screening for Wolfram syndrome in affected families and for Wolfram syndrome-carrier status in subjects with psychiatric disorders or diabetes mellitus will require complete analysis of exon 8 and upstream exons.

013 Low insulin-like growth factor-1 in CSF of children with progressive encephalopathy hypsarrhythmia and optic atrophy (PEHO) syndrome, and cerebellar degeneration

013 Low insulin-like growth factor-1 in CSF of children with progressive encephalopathy hypsarrhythmia and optic atrophy (PEHO) syndrome, and cerebellar degeneration

A gene encoding a transmembrane protein is mutated in patients with diabetes mellitus and optic atrophy (Wolfram syndrome).

Wolfram syndrome (WFS; OMIM 222300) is an autosomal recessive neurodegenerative disorder defined by young-onset non-immune insulin-dependent diabetes mellitus and progressive optic atrophy. Linkage to markers on chromosome 4p was confirmed in five families. On the basis of meiotic recombinants and disease-associated haplotypes, the WFS gene was localized to a BAC/P1 contig of less than 250 kb. Mutations in a novel gene (WFS1) encoding a putative transmembrane protein were found in all affected individuals in six WFS families, and these mutations were associated with the disease phenotype. WFS1 appears to function in survival of islet beta-cells and neurons.

The Progressive Outer Retinal Necrosis Syndrome: Successful Treatment With Combination Antiviral Therapy

To assess a two-drug combination of antiviral therapy for the progressive outer retinal necrosis syndrome (PORN), given the current poor outcome with acyclovir alone. A retrospective review was performed on six consecutive patients who were diagnosed with PORN and were treated with various combinations of intravenous or oral plus intravenous antiviral therapy. The relative efficacies of these modalities were compared. Six eyes of six patients showed active retinitis at the time of presentation. Three patients had unilateral retinitis, and the remaining patients had necrotic, end-stage disease in their fellow eye. All the patients were treated with combination therapy, consisting of either ganciclovir and acyclovir (three patients), foscarnet and ganciclovir (two patients), or foscarnet and acyclovir (one patient). Standard induction doses were employed. During the combination therapy, all six eyes showed resolution of the retinitis, manifested by complete fading of the original retinal lesions and an absence of new lesion formation. At the final follow-up, the areas of prior active retinitis had resolved and remained quiescent. A mild recurrence developed in one eye when ganciclovir and foscarnet were both tapered to a single daily dose. This recurrence promptly resolved with reinduction (twice daily) dosing. Two patients maintained a visual acuity of 20/50 or better in their involved eye for the duration of follow-up (38 and 27 weeks, respectively). One patient maintained a visual acuity of 20/40 for 14 weeks. The remaining three patients had macula-off retinal detachments despite resolution of active retinitis. In addition, for the duration of follow-up, one of the three patients with unilateral disease had retinitis in the uninvolved eye; all three uninvolved fellow eyes maintained a visual acuity of 20/20. One patient had progressive optic atrophy. Prolonged combination antiviral therapy for PORN may successfully arrest the progression of retinitis, maintain remission, and prevent involvement of the fellow eye. Furthermore, if aggressive therapy is begun early, good vision may be preserved.

Progressive dystonia with optic atrophy in a Jewish–Iraqi family

The combination of progressive dystonia and optic atrophy is extremely rare and its morphological, metabolic and genetic basis is unknown. In a family of 9 children (8 males) born to consanguineous Israeli-Jewish–Iraqi parents, we identified four brothers who developed the syndrome at the end of the first decade. Patients had hemi or bilateral dystonia associated with striatal, mainly putaminal, atrophy on CT and MRI, various degrees of optic atrophy, minimal corticospinal tract involvement, normal intelligence and no peripheral nervous system or systemic abnormalities. No causative metabolic defect was identified. None of the several known mitochondrial DNA mutations associated with Leber's hereditary optic neuropathy (LHON) or with LHON with dystonia were detected. Likewise, linkage to the idiopathic torsion dystonia region on chromosome 9q34 was excluded. It is suggested that this entity in our patients might be due to a yet unidentified genomic, autosomal recessive mutation.

Fusiform aneurysms (dolichoectasia) of the internal carotid artery as cause of optic nerve damage

Dolichoectasia of cerebral vessels most often occurs in middle-aged or elderly patients, also occasionally in children and in subjects with neurofibromatosis type NF-i. It seems that less atherosclerosis but severe deficiency of reticular fibers in the media associated with extensive defects in the elastic lamina represents the main factor in the pathogenesis of these ectasias. In contrast to saccular aneurysms, the fusiform aneurysms never cause subarachnoid hemorrhage. Those originating from the internal carotid artery produce damage to the optic nerve by direct pressure or by impairment of the circulation of nutrient vessels. Visual loss may be slowly progressive or acute, affecting one eye weeks or years before the other. Visual field defects are not specific: altitudinal, temporal, constriction, central or cecocentral scotomas. Progressive optic atrophy on the affected side is the rule; sometimes papilledema on the other side can mimick a Foster-Kennedy syndrome. The treatment possibilities are discussed: for example, surgical excision of the ectatic vessel region, decompression of the optic nerve by separation from the ectatic vessel (interposition of muscle tissue), or unroofing the optic canal and subsequent cutting of the dural fold and the dural sheath of the optic nerve.

Refinement of the dominant optic atrophy locus (OPA1) to a 1.4-cM interval on chromosome 3q28-3q29, within a 3-Mb YAC contig.

Dominant optic atrophy, type Kjer, is an autosomal dominant eye disease that is characterized by progressive optic atrophy with onset in early childhood, decrease of visual acuity, colour vision defects and centrocecal scotoma. By examination of 5 Danish families and the use of polymorphic markers, we have refined the localization of the OPA1 locus and assigned it to a 1.4-cM interval on chromosome 3q28-3q29, between markers D3S3669 and D3S3562. This localizes the gene on a 3-Mb YAC contig covering the disease locus. We have also located a possible candidate gene HRY to this contig.

Photographic Documentation of the Loss of Medullated Nerve Fibers of the Retina in Uncontrolled Primary Open Angle Glaucoma

We report the first case of retinal myelin loss associated with uncontrolled primary open angle glaucoma (POAG). The clinical features, visual fields, and serial disc photos documenting the changes are described. The literature regarding this phenomenon in other forms of optic neuropathy and the specific implications in glaucoma patients are discussed. A 75-year-old black man with POAG had medullated nerve fibers of the retina bilaterally abutting the optic discs inferonasally. Optic disc appearance and visual fields were stable over 6 years. The patient was then lost to follow-up for 2 years and returned with elevated intraocular pressures (IOPs), visual acuity and field loss, progressive optic disc damage, peripapillary atrophy, and disappearance of retinal myelin on the left greater than the right. Retinal myelin loss occurred in areas of nerve fiber layer dropout. Loss of medullated nerve fibers in the retina occurs secondary to anterograde axonal degeneration as a nonspecific response to any form of optic atrophy. The apparent paucity of glaucoma patients with retinal myelin may be due to late referral rather than any inherent protective effect of retinal myelin against elevated IOP.

Morbidity and mortality in the Wolfram syndrome.

To determine the major causes of morbidity and mortality in the autosomal recessive Wolfram syndrome, which is defined by diabetes and bilateral progressive optic atrophy with onset in childhood or adolescence. We abstracted and reviewed the medical records of 68 confirmed cases of Wolfram syndrome identified through a nationwide survey of endocrinologists, ophthalmologists, institutes, and homes for the blind. We also reviewed all available autopsy records. The most common causes of morbidity and mortality were the neurological manifestations of this syndrome and the complications of urinary tract atony. There was a lower frequency of diabetic ketoacidosis, no histologically proven diabetic glomerulosclerosis, and less severe, more slowly progressive, diabetic retinopathy than in classic type I diabetic patients. Mortality in Wolfram syndrome is much higher than in type I diabetes; 60% of Wolfram syndrome patients die by age 35. Recognition of these clinical differences from classic type I diabetes is important for the proper management of Wolfram syndrome patients. Identification of Wolfram syndrome patients among all diabetic patients presenting in childhood or adolescence is important because the management of patients with this syndrome is different from that of patients with classic type I diabetes.

Linkage of the gene for Wolfram syndrome to markers on the short arm of chromosome 4

Wolfram syndrome is an autosomal recessive disorder defined by the occurrence of diabetes mellitus and progressive bilateral optic atrophy. Wolfram syndrome homozygotes develop widespread nervous system abnormalities; in particular, they exhibit severe behavioural difficulties that often lead to suicide attempts or psychiatric hospitalizations. The Wolfram syndrome gene also predisposes heterozygous carriers to psychiatric disorders, and may contribute significantly to the overall burden of psychiatric illness. Based on a linkage analysis of 11 families segregating for this syndrome using microsatellite repeat polymorphisms throughout the human genome, we found the Wolfram syndrome gene to be linked to markers on the short arm of human chromosome 4, with Zmax = 6.46 at theta = 0.02 for marker D4S431.

Hallervorden-Spatz syndrome and brain iron metabolism

• Aberrant iron metabolism in the brain is typified by Hallervorden-Spatz syndrome. In this disorder, large amounts of iron are deposited in the globus pallidus and the pars reticulata of the substantia nigra. It is characterized by extrapyramidal dysfunction, as demonstrated by dystonia, rigidity, and choreoathetosis; onset during the first two decades of life; and progression of signs and symptoms. Corroborative findings include corticospinal tract involvement, ie, spasticity and extensor toe signs, progressive intellectual impairment, retinitis pigmentosa and optic atrophy (usually associated visual evoked response and electroretinogram abnormalities), seizures, familial occurrence, hypointense areas in the basal ganglia on magnetic resonance imaging scans (particularly in the substantia nigra), abnormal cytosomes in circulating lymphocytes, and sea-blue histiocytes in bone marrow. Iron function in normal brain metabolism is manifold, but high concentrations of iron in the basal ganglia area may signal a unique relationship. Data support the likelihood that iron plays a role in the modulation of dopamine binding to postsynaptic receptors. In addition, transferrin receptors and iron are also concentrated in oligodendrocytes in normal brain and, thus, may have a function in myelination. A role of iron also seems likely in oxidation and peroxidation reactions involving membranes and DNA, a capability that becomes uncontrolled when protective biologic mechanisms become inadequate.

Choristoma of the Optic Nerve and Chiasm

A 21-year-old patient with a biopsy-proved choristomatous malformation of the optic nerve and chiasm is presented. The patient experienced progressive unilateral vision loss and optic atrophy. A gadolinium-enhanced magnetic resonance image demonstrated chiasmal involvement that was not evident on computed tomographic scan or visual field testing. We believe this is the third reported case of a choristomatous malformation of the optic nerve and chiasm and the first report of magnetic resonance imaging findings.

Hallervorden-Spatz Syndrome and Brain Iron Metabolism

Aberrant iron metabolism in the brain is typified by Hallervorden-Spatz syndrome. In this disorder, large amounts of iron are deposited in the globus pallidus and the pars reticulata of the substantia nigra. It is characterized by extrapyramidal dysfunction, as demonstrated by dystonia, rigidity, and choreoathetosis; onset during the first two decades of life; and progression of signs and symptoms. Corroborative findings include corticospinal tract involvement, ie, spasticity and extensor toe signs, progressive intellectual impairment, retinitis pigmentosa and optic atrophy (usually associated visual evoked response and electroretinogram abnormalities), seizures, familial occurrence, hypointense areas in the basal ganglia on magnetic resonance imaging scans (particularly in the substantia nigra), abnormal cytosomes in circulating lymphocytes, and sea-blue histiocytes in bone marrow. Iron function in normal brain metabolism is manifold, but high concentrations of iron in the basal ganglia area may signal a unique relationship. Data support the likelihood that iron plays a role in the modulation of dopamine binding to postsynaptic receptors. In addition, transferrin receptors and iron are also concentrated in oligodendrocytes in normal brain and, thus, may have a function in myelination. A role of iron also seems likely in oxidation and peroxidation reactions involving membranes and DNA, a capability that becomes uncontrolled when protective biologic mechanisms become inadequate.

Oculo-auditory Syndromes

This unique volume gives us the best understanding to date of the two higher sensory systems, the ocular and the auditory, which are very complex but have common characteristics. Contributors from the interrelated fields of basic science clearly point out the overlapping anatomy, embryology, and physiology, which are liable to produce complicated and rare clinical syndromes. The common ectodermal origin of the eye and ear logically leads to anatomic similarities, especially as regards circulation and neurovegetative function. This developmental pattern is responsible for oculoauditory syndromes due to genetic defects affecting the neuroectoderm, including Usher's syndrome (retinitis pigmentosa and dysacousia), Alstrom's syndrome (retinitis pigmentosa, obesity, deafness, and diabetes mellitus), Norrie's disease (oculoacoustic cerebral degeneration), Refsum's disease (phytanic acid storage disease), and Konigsmark's syndrome (congenital deafness and progressive optic atrophy). Genetic enzymatic defects affecting mesenchymal tissues are illustrated by Goldenhar's syndrome (oculoauriculovertebral dysplasia) and Waardenburg's syndrome, among others. This book is helpful