Is phenotype difference in severe myoclonic epilepsy in infancy related to SCN1A mutations?

Iori Ohmori, Yoko Ohtsuka, Mamoru Ouchida, Tatsuya Ogino, Satoshi Maniwa, Kenji Shimizu, Eiji Oka

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)


We classified 28 patients with severe myoclonic epilepsy in infancy (SME) according to the presence or absence of myoclonic seizures and/or atypical absences. Eleven of the patients had myoclonic seizures and/or atypical absences, and we refer to this condition as 'typical SME (TSME)'. Seventeen of the patients had only segmental myoclonias, and we refer to this condition as 'borderline SME (BSME)'. We then analyzed the electroclinical and genetic characteristics of these two groups. Ten of the 11 TSME patients had a photoparoxysmal response at some time during their clinical course, while none of the BSME patients showed this response. TSME and BSME showed a significant difference in regard to gender ratio: female dominance in TSME and male dominance in BSME (P=0.008). The detection rate of the voltage-gated sodium channel α1-subunit (SCN1A) gene mutations was 72.7 and 88.2% in TSME and BSME, respectively. There was no difference in the type or rate of mutation between TSME and BSME. We conclude that TSME and BSME show distinct differences in photoparoxysmal response and gender, which might be caused by some genetic mechanism(s) other than the SCN1A gene mutation.

Original languageEnglish
Pages (from-to)488-493
Number of pages6
JournalBrain and Development
Issue number7
Publication statusPublished - Oct 2003


  • Generalized epilepsy with febrile seizures plus
  • Phenotype
  • SCN1A
  • Severe myoclonic epilepsy in infancy

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Developmental Neuroscience
  • Clinical Neurology


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