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Krygier, M.* ; Sitek, E.J.* ; Chylińska, M.* ; Ziętkiewicz, S.* ; Zawadzka, M.* ; Dulski, J.* ; Schinwelski, M.* ; Kostrzewa, G.* ; Wierzba, J.* ; Płoski, R.* ; Zech, M. ; Mazurkiewicz-Bełdzińska, M.*

Beyond SGCE: Expanding the clinical and molecular spectrum of KCTD17- and KCNN2-related myoclonus-dystonia.

Front. Neurol. 17:1728361 (2026)
Publ. Version/Full Text Research data DOI PMC
Open Access Gold
Creative Commons Lizenzvertrag
Myoclonus-dystonia syndrome (MDS) is a clinically and genetically heterogeneous movement disorder characterized by myoclonus and dystonia as its core features. While mutations in the epsilon-sarcoglycan gene (SGCE) account for most familial cases, heterozygous pathogenic variants in KCTD17 and KCNN2 have recently been described as novel genetic causes of MDS. We describe three patients from two Polish families presenting with progressive movement disorder combined with other features. Exome sequencing (ES) identified a novel heterozygous KCTD17 variant c.461 T > A, p.(Met154Lys) in a five-year-old girl with abnormal gait, postural instability, myoclonus, and tongue dyskinesia. In a 38-year-old woman and her 17-year-old daughter, both showing tremor, myoclonus, dystonia, and psychiatric symptoms, ES detected a heterozygous canonical splice-site c.1780-2A > G variant in KCNN2. Neuropsychological evaluation suggested a gene-specific effect of KCNN2 on psychiatric and cognitive functioning, including significant episodic memory impairment. This study broadens the clinical and molecular spectrum of KCTD17- and KCNN2-related MDS and highlights distinctive features compared with SGCE-MDS, focusing on disease progression, treatment response, and neuropsychiatric involvement. Recognition of these patterns may guide molecular diagnosis and the management of specific MDS types.
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Publication type Article: Journal article
Document type Scientific Article
Keywords Kcnn2 ; Kctd17 ; Sgce ; Dystonia ; Memory Impairment ; Myoclonus ; Neuropsychiatric Symptoms ; Pediatric Movement Disorders; Mutation; Patient; Sk2
ISSN (print) / ISBN 1664-2295
e-ISSN 1664-2295
Quellenangaben Volume: 17, Issue: , Pages: , Article Number: 1728361 Supplement: ,
Publisher Frontiers
Publishing Place Lausanne
Reviewing status Peer reviewed
Grants German Federal Ministry of Education and Research
Else Krner-Fresenius-Stiftung
Institute for Advanced Study
Technical University of Munich
German Research Foundation