Isolated eyelid closure myotonia in two families with sodium channel myotonia

Bas C. Stunnenberg, Hendrika B. Ginjaar, J. Trip, C. G. Faber, Baziel G. M. van Engelen, G. Drost*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Sodium channelopathies (NaCh), as part of the non-dystrophic myotonic syndromes (NDMs), reflect a heterogeneous group of clinical phenotypes accompanied by a generalized myotonia. Because of recent availability of diagnostic genetic testing in NDM, there is a need for identification of clear clinical genotype-phenotype correlations. This will enable clinicians to distinguish NDMs from myotonic dystrophy, thus allowing them to inform patients promptly about the disease, perform genetic counseling, and orient therapy (Vicart et al. Neurol Sci 26:194-202, 2005). We describe the first distinctive clinical genotype-phenotype correlation within NaCh: a strictly isolated eyelid closure myotonia associated with the L250P mutation in SCN4A. Using clinical assessment and needle EMG, we identified this genotype-phenotype correlation in six L250P patients from one NaCh family and confirmed this finding in another, unrelated NaCh family with three L250P patients.
Original languageEnglish
Pages (from-to)257-260
Issue number2
Publication statusPublished - May 2010


  • Non-dystrophic myotonic syndromes
  • Sodium channelopathies
  • SCN4A
  • Na(v)1,4
  • Genotype-phenotype correlation


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