Electroencephalographic findings and genetic characterization of two brothers with IQSEC2 pathogenic variant

Tatsuro Izumi, Yu Aihara, Atsuo Kikuchi, Shigeo Kure

Research output: Contribution to journalArticlepeer-review


Two brothers with an IQSEC2 pathogenic variant presented with early onset intellectual disability, intractable epileptic seizures, autism spectrum disorders, postnatal microcephalus and slowly progressive rigid-spasticity. Their epileptic seizures were characterized by intractability, early onset epileptic spasms, and then clusters of tonic/tonic-clonic seizures, exacerbated by valproate. Electroencephalography showed periodic discharges, including periodic high voltage slow complexes and burst-suppression activity. Whole exome sequencing, using DNA from peripheral blood of both brothers, identified a pathogenic variant, c.2776 C > T, p.(Arg 926*) in exon 9 of IQSEC2 (NM 001111125.3). Their parents and another brother did not have this variant, which may suggest that maternal gonadal mosaicism is the most likely mechanism.

Original languageEnglish
Pages (from-to)652-656
Number of pages5
JournalBrain and Development
Issue number5
Publication statusPublished - 2021 May


  • Genetic counseling
  • IQSEC2 pathogenic variant
  • Periodic discharges on EEG

ASJC Scopus subject areas

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


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