Progressive myoclonus epilepsies: diagnostic yield with next-generation sequencing in previously unsolved cases
Details
Publication Year 2021-12, Volume 7, Issue #6, Page e641
Journal Title
Neurology Genetics
Abstract
Background and Objectives: To assess the current diagnostic yield of genetic testing for the progressive myoclonus epilepsies (PMEs) of an Italian series described in 2014 where Unverricht-Lundborg and Lafora diseases accounted for approximately 50% of the cohort. Methods: Of 47/165 unrelated patients with PME of indeterminate genetic origin, 38 underwent new molecular evaluations. Various next-generation sequencing (NGS) techniques were applied including gene panel analysis (n = 7) and/or whole-exome sequencing (WES) (WES singleton n = 29, WES trio n = 7, and WES sibling n = 4). In 1 family, homozygosity mapping was followed by targeted NGS. Clinically, the patients were grouped in 4 phenotypic categories: "Unverricht-Lundborg disease-like PME," "late-onset PME," "PME plus developmental delay," and "PME plus dementia." Results: Sixteen of 38 (42%) unrelated patients reached a positive diagnosis, increasing the overall proportion of solved families in the total series from 72% to 82%. Likely pathogenic variants were identified in NEU1 (2 families), CERS1 (1 family), and in 13 nonfamilial patients in KCNC1 (3), DHDDS (3), SACS, CACNA2D2, STUB1, AFG3L2, CLN6, NAXE, and CHD2. Across the different phenotypic categories, the diagnostic rate was similar, and the same gene could be found in different phenotypic categories. Discussion: The application of NGS technology to unsolved patients with PME has revealed a collection of very rare genetic causes. Pathogenic variants were detected in both established PME genes and in genes not previously associated with PME, but with progressive ataxia or with developmental encephalopathies. With a diagnostic yield >80%, PME is one of the best genetically defined epilepsy syndromes.
Publisher
Am Acad Neurology
WEHI Research Division(s)
Population Health And Immunity
PubMed ID
34786481
Open Access at Publisher's Site
https://doi.org/10.1212/NXG.0000000000000641
Rights Notice
Refer to copyright notice on published article.


Creation Date: 2021-12-07 12:03:55
Last Modified: 2021-12-07 12:13:32
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