title: Two cases of early-onset myoclonic seizures with continuous parietal delta activity caused by EEF1A2 mutations.
abstract: BACKGROUND
  Mutations in the elongation factor 1 alpha 2 (EEF1A2) gene have recently been shown to cause severe intellectual disability with early-onset epilepsy. The specific manifestations of mutations in this gene remain unknown.
  
  
  METHODS
  We report two cases of severe intellectual disability accompanied by early-onset epilepsy with continuous delta activity evident on electroencephalography. Both cases presented with developmental delay and repetitive myoclonic seizures in early infancy. Both cases showed continuous high-voltage delta activity over both parietal areas when awake, as revealed by interictal electroencephalograms. After the emergence of continuous delta activity, development stagnated. One case showed some development after relief of the seizures and epileptic activity, but drug resistant seizures recurred, and the development again became stagnant. In both cases, a de novo recurrent heterozygous mutation in EEF1A2 [c.364G>A (p.E122K)] was identified by whole-exome sequencing.
  
  
  CONCLUSIONS
  This report provides clinical data on epileptic encephalopathy in patients with EEF1A2 mutation. Continuous high-voltage delta activity seen over both parietal areas may be a unique manifestation of EEF1A2 mutation. Epileptic activity may aggravate the effect of the mutation on brain development.
authors.affiliation: Department of Pediatric Neurology, Takuto Rehabilitation Center for Children, Sendai, Miyagi, Japan. Electronic address: inutakejp@yahoo.co.jp.
authors.forename: Takehiko
authors.initials: T
authors.lastname: Inui
authors.affiliation: Department of Pediatrics, Nagoya City West Medical Center, Nagoya, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Kobayashi
authors.affiliation: Department of Pediatrics, Nagoya City West Medical Center, Nagoya, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Ashikari
authors.affiliation: Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Sato
authors.affiliation: Department of Pediatric Neurology, Takuto Rehabilitation Center for Children, Sendai, Miyagi, Japan.
authors.forename: Wakaba
authors.initials: W
authors.lastname: Endo
authors.affiliation: Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Mitsugu
authors.initials: M
authors.lastname: Uematsu
authors.affiliation: Department of Radiology, Teikyo University Hospital, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Oba
authors.affiliation: Department of Human Genetics, Yokohama City University, Graduate School of Medicine, Yokohama, Japan.
authors.forename: Hirotomo
authors.initials: H
authors.lastname: Saitsu
authors.affiliation: Department of Human Genetics, Yokohama City University, Graduate School of Medicine, Yokohama, Japan.
authors.forename: Naomichi
authors.initials: N
authors.lastname: Matsumoto
authors.affiliation: Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Kure
authors.affiliation: Department of Pediatric Neurology, Takuto Rehabilitation Center for Children, Sendai, Miyagi, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Haginoya
mesh_terms: D002675:Child, Preschool; D004569:Electroencephalography / Q000379:methods; D004831:Epilepsies, Myoclonic / Q000150:complications / Q000235:genetics*; D004827:Epilepsy / Q000150:complications / Q000235:genetics; D005260:Female; D006801:Humans; D008607:Intellectual Disability / Q000150:complications; D008297:Male; D020125:Mutation, Missense; D010296:Parietal Lobe / Q000503:physiopathology; D020648:Peptide Elongation Factor 1 / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D010641:Phenotype; D012640:Seizures / Q000150:complications
chemical_list: C503234:EEF1A2 protein, human; D020648:Peptide Elongation Factor 1
keywords: EEF1A2; Epilepsy; Genetics; High voltage delta activity; Intellectual disability; Myoclonic seizure; Pediatrics