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Progressive myoclonus epilepsies-Residual unsolved cases have marked genetic heterogeneity including dolichol-dependent protein glycosylation pathway genes.

ABSTRACT: Progressive myoclonus epilepsies (PMEs) comprise a group of clinically and genetically heterogeneous rare diseases. Over 70% of PME cases can now be molecularly solved. Known PME genes encode a variety of proteins, many involved in lysosomal and endosomal function. We performed whole-exome sequencing (WES) in 84 (78 unrelated) unsolved PME-affected individuals, with or without additional family members, to discover novel causes. We identified likely disease-causing variants in 24 out of 78 (31%) unrelated individuals, despite previous genetic analyses. The diagnostic yield was significantly higher for individuals studied as trios or families (14/28) versus singletons (10/50) (OR = 3.9, p value = 0.01, Fisher's exact test). The 24 likely solved cases of PME involved 18 genes. First, we found and functionally validated five heterozygous variants in NUS1 and DHDDS and a homozygous variant in ALG10, with no previous disease associations. All three genes are involved in dolichol-dependent protein glycosylation, a pathway not previously implicated in PME. Second, we independently validate SEMA6B as a dominant PME gene in two unrelated individuals. Third, in five families, we identified variants in established PME genes; three with intronic or copy-number changes (CLN6, GBA, NEU1) and two very rare causes (ASAH1, CERS1). Fourth, we found a group of genes usually associated with developmental and epileptic encephalopathies, but here, remarkably, presenting as PME, with or without prior developmental delay. Our systematic analysis of these cases suggests that the small residuum of unsolved cases will most likely be a collection of very rare, genetically heterogeneous etiologies.

SUBMITTER: Courage C

PROVIDER: S-EPMC8059372 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Introduction: Progressive myoclonic epilepsies (PMEs) are a heterogenous group of genetic diseases presenting with epilepsy, cognitive impairment, and severe action myoclonus, which can severely affect daily life activities and independent walking ability. Perampanel is a recent commercially available antiseizure medication with high efficacy against generalized seizures. Some reports supported the role of perampanel in ameliorating action myoclonus in PMEs. Here, we aimed to describe a case series and provide a systematic literature review on perampanel effects on PMEs. Methods: We report the perampanel effectiveness on myoclonus, daily life activities, and seizures on an original Italian multicenter case series of 11 individuals with PMEs. Then, using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, we performed a systematic review on perampanel effect on myoclonus and disability in PMEs. We searched PubMed, Scopus, and Google Scholar articles on perampanel and PMEs up to June 2020. No prospective trials were found. We reviewed 11 case series manuscripts reporting 104 cases of different PMEs. Results: Here, we are reporting the effectiveness of perampanel in five individuals affected by Unverricht-Lundborg disease, three by Lafora disease, two by sialidosis, and one by an undetermined PME. Nine out of 11 individuals improved their disability related to the action myoclonus (two with Lafora disease did not). Among the 104 persons with PMEs collected by the systematic review, we found that more than half of the patients receiving perampanel exhibited an amelioration of action myoclonus and, consequently, of their independence in daily life activities. The Unverricht-Lundborg disease seemed to show the best clinical response to perampanel, in comparison with the other more severe PMEs. A significant seizure reduction was achieved by almost all persons with active epilepsy. Only 11% of PME patients dropped out due to inefficacy. Conclusions: Perampanel demonstrated a beneficial effect with regard to action myoclonus, disability, and seizures and was well-tolerated in people with PMEs, independently from their genetic diagnosis. Given the limited scientific evidence, broader prospective trials should be encouraged.

Project description:BackgroundThe clinical demarcation of the syndrome progressive myoclonus ataxia is unclear, leading to a lack of recognition and difficult differentiation from other neurological syndromes.ObjectivesThe objective of this study was to apply a refined definition of progressive myoclonus ataxia and describe the clinical characteristics in patients with progressive myoclonus ataxia and with isolated cortical myoclonus.MethodsA retro- and prospective analysis was performed in our tertiary referral center between 1994 and 2014. Inclusion criteria for progressive myoclonus ataxia patients were the presence of myoclonus and ataxia with or without infrequent (all types, treatment responsive) epileptic seizures. Inclusion criteria for isolated cortical myoclonus was the presence of isolated cortical myoclonus. Clinical and electrophysiological characteristics data were systematically scored.ResultsA total of 14 progressive myoclonus ataxia patients (males, 7; females, 7), median age 14.5 years, and 8 isolated cortical myoclonus patients (males, 2; females, 6), median age 23.5 years, were identified. In 93% of the progressive myoclonus ataxia patients, ataxia started first (median 2 years) followed by myoclonus (4 years) and finally infrequent epilepsy (9.3 years), with a progressive course in 93%. In 64% of the progressive myoclonus ataxia patients, a genetic underlying etiology was identified, including 3 not earlier reported causative progressive myoclonus ataxia genes. In isolated cortical myoclonus patients, myoclonus started at (median) 12 years with progression over time in 63% and a single epileptic seizure in 1 patient. No genetic causes were identified.ConclusionUsing a refined definition, we could create a rather homogenous progressive myoclonus ataxia group. Patients with isolated cortical myoclonus have a different course and do not appear to evolve in progressive myoclonus ataxia. The refined progressive myoclonus ataxia definition is a successful first step toward creating a separate syndrome for both clinical practice and future genetic research. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

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Progressive myoclonus epilepsies-Residual unsolved cases have marked genetic heterogeneity including dolichol-dependent protein glycosylation pathway genes.

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