Retinal Neuronal Loss in Visually Asymptomatic Patients With Myoclonic Epilepsy With Ragged-Red Fibers.

BACKGROUND: Myoclonic epilepsy with ragged-red fibers (MERRF, OMIM, #545000) is a rare neurological condition mostly caused by the m.8344A>G mitochondrial DNA pathogenic variant, which can variably affect multiple tissues, including the retina and optic nerve. We report detection of visually asymptomatic neuroretinal loss in 3 patients with genetically confirmed MERRF, using spectral domain optical coherence tomography (SD-OCT). METHODS: All patients underwent a complete ophthalmic examination including assessments of visual acuity, color vision, pupillary reactions, extraocular movements, applanation tonometry, slit-lamp, and dilated fundus examinations. Standard automated perimetry or Goldmann kinetic perimetry was performed, as well as fundus photographs and SD-OCT of the optic nerve head and macula. RESULTS: Despite the absence of visual symptoms in all patients, and normal visual acuity and visual fields in 1 patient, the 3 genetically confirmed patients (point mutations m.8344A>G; age range: 18-62 years) with MERRF-related neurological manifestations, displayed thinning of the retinal nerve fiber layer and variable alterations of the macular ganglion cell complex. CONCLUSIONS: Visually asymptomatic patients with genetically confirmed MERRF can display features of structural neuroretinal loss, quantifiable with SD-OCT. Further investigations are needed to establish whether OCT can assess early neurodegeneration in MERRF.

Increased steroidogenesis promotes early-onset and severe vision loss in females with OPA1 dominant optic atrophy.

OPA1 mutations are responsible for autosomal dominant optic atrophy (ADOA), a progressive blinding disease characterized by retinal ganglion cell (RGC) degeneration and large phenotypic variations, the underlying mechanisms of which are poorly understood. OPA1 encodes a mitochondrial protein with essential biological functions, its main roles residing in the control of mitochondrial membrane dynamics as a pro-fusion protein and prevention of apoptosis. Considering recent findings showing the importance of the mitochondrial fusion process and the involvement of OPA1 in controlling steroidogenesis, we tested the hypothesis of deregulated steroid production in retina due to a disease-causing OPA1 mutation and its contribution to the visual phenotypic variations. Using the mouse model carrying the human recurrent OPA1 mutation, we disclosed that Opa1 haploinsufficiency leads to very high circulating levels of steroid precursor pregnenolone in females, causing an early-onset vision loss, abolished by ovariectomy. In addition, steroid production in retina is also increased which, in conjunction with high circulating levels, impairs estrogen receptor expression and mitochondrial respiratory complex IV activity, promoting RGC apoptosis in females. We further demonstrate the involvement of Muller glial cells as increased pregnenolone production in female cells is noxious and compromises their role in supporting RGC survival. In parallel, we analyzed ophthalmological data of a multicentre OPA1 patient cohort and found that women undergo more severe visual loss at adolescence and greater progressive thinning of the retinal nerve fibres than males. Thus, we disclosed a gender-dependent effect on ADOA severity, involving for the first time steroids and Müller glial cells, responsible for RGC degeneration.

Improved locus-specific database for OPA1 mutations allows inclusion of advanced clinical data.

Autosomal-dominant optic atrophy (ADOA) is the most common inherited optic neuropathy, due to mutations in the optic atrophy 1 gene (OPA1) in about 60%-80% of cases. At present, the clinical heterogeneity of patients carrying OPA1 variants renders genotype-phenotype correlations difficulty. Since 2005, when we published the first locus-specific database (LSDB) dedicated to OPA1, a large amount of new clinical and genetic knowledge has emerged, prompting us to update this database. We have used the Leiden Open-Source Variation Database to develop a clinico-biological database, aiming to add clinical phenotypes related to OPA1 variants. As a first step, we validated this new database by registering several patients previously reported in the literature, as well as new patients from our own institution. Contributors may now make online submissions of clinical and molecular descriptions of phenotypes due to OPA1 variants, including detailed ophthalmological and neurological data, with due respect to patient anonymity. The updated OPA1 LSDB (http://opa1.mitodyn.org/) should prove useful for molecular diagnoses, large-scale variant statistics, and genotype-phenotype correlations in ADOA studies.

MOG-Ab prevalence in optic neuritis and clinical predictive factors for diagnosis.

OBJECTIVE: What is the proportion of antibodies to myelin oligodendrocyte glycoprotein (MOG-Ab) in optic neuritis (ON) in adults and what would be the ON presentation for which MOG-Ab should be tested? METHODS: Multicentric prospective study conducted during 1 year on all patients diagnosed with acute ON in all ophthalmological units in hospitals in a region in western France. RESULTS: Sixty-five patients were included. MOG-Ab prevalence was 14% (9/65) during an acute ON and 13% (7/55) after exclusion of patients already diagnosed with multiple sclerosis (MS) (8) or MOG+ON (2). Compared with MS and clinically isolated syndrome, MOG+ON had no female preponderance (67% of men in case of MOG+ON and 22% of men in case of MS and clinically isolated syndrome, p<0.05) were more often bilateral (44% vs 3%, p<0.005) and associated with optic disc swelling (ODS) (78% vs 14%, p<0.001). To predict MOG+ON, the positive predictive values (PPVs) of male sex, ODS and bilateral involvement were 29% (95% CI 9% to 48%), 41% (95% CI 18% to 65%) and 40% (95% CI 10% to 70%), respectively, while the negative predictive values (NPV) were 93% (95% CI 86% to 100%), 96% (95% CI 90% to 100%) and 91% (95% CI 83% to 99%), respectively. The combined factor 'ODS or bilateral or recurrent ON' was the best compromise between PPV (31% (95% CI 14% to 48%)) and NPV (100% (95% CI 100% to 100%)). CONCLUSION: Among ON episodes, MOG-Ab were found in 14% of cases. MOG+ON occurred without female preponderance and was significantly associated with ODS and/or bilateral ON. Testing MOG-Ab only in patients presenting with ODS or bilateral or recurrent ON would limit MOG-Ab tests to fewer than half of all patients without the risk of missing any MOG+ON cases.

OPA1: 516 unique variants and 831 patients registered in an updated centralized Variome database.

BACKGROUND: The dysfunction of OPA1, a dynamin GTPase involved in mitochondrial fusion, is responsible for a large spectrum of neurological disorders, each of which includes optic neuropathy. The database dedicated to OPA1 ( https://www.lovd.nl/OPA1 ), created in 2005, has now evolved towards a centralized and more reliable database using the Global Variome shared Leiden Open-source Variation Database (LOVD) installation. RESULTS: The updated OPA1 database, which registers all the patients from our center as well as those reported in the literature, now covers a total of 831 patients: 697 with isolated dominant optic atrophy (DOA), 47 with DOA "plus", and 83 with asymptomatic or unclassified DOA. It comprises 516 unique OPA1 variants, of which more than 80% (414) are considered pathogenic. Full clinical data for 118 patients are documented using the Human Phenotype Ontology, a standard vocabulary for referencing phenotypic abnormalities. Contributors may now make online submissions of phenotypes related to OPA1 mutations, giving clinical and molecular descriptions together with detailed ophthalmological and neurological data, according to an international thesaurus. CONCLUSIONS: The evolution of the OPA1 database towards the LOVD, using unified nomenclature, should ensure its interoperability with other databases and prove useful for molecular diagnoses based on gene-panel sequencing, large-scale mutation statistics, and genotype-phenotype correlations.

Optic nerve and visual pathways primary glioblastoma treated with radiotherapy and temozolomide chemotherapy.

PURPOSE: Primary malignant gliomas of the optic nerves are rare tumors of adulthood, progressing rapidly to blindness and to death within several months, regardless of the type of treatment. Recently, treatments associating radiotherapy and temozolomide have been used in other types of glioblastomas, but their impact on optic nerve malignant gliomas is not known. METHODS: This was a retrospective case series of 2 patients diagnosed with primary optic nerve and chiasm glioblastoma (GBM), treated with radiotherapy and concomitant temozolomide. RESULTS: A 74-year-old man presented with visual loss caused by an infiltrative and enhancing lesion, affecting the left optic nerve and the chiasm, subsequently confirmed as GBM World Health Organization (WHO) grade IV. The patient was treated with external conformal radiotherapy (54 Gy over 42 days) and concomitant chemotherapy with temozolomide (75 mg/m2/day), followed by 6 monthly cycles of adjuvant treatment (250 mg/day for 5 days). The second patient was a 74-year-old woman diagnosed with bilateral visual loss due to pathologically confirmed GBM (WHO grade IV). She was treated with temozolomide (220 mg/day) for 1 month, followed by radiotherapy (54 Gy over 42 days) and temozolomide chemotherapy (75 mg/m2/day). There was no adjuvant regimen. This treatment resulted in disease stabilization and partial preservation of vision during 12 months for patient 1, 8 months for patient 2. Survival after first examination was 15 and 11 months, respectively. CONCLUSIONS: Combined radiotherapy and temozolomide may be an alternative treatment in optic nerve and visual pathways primary GBM, potentially providing a longer survival.