GRIN1 mutations cause encephalopathy with infantile-onset epilepsy, and hyperkinetic and stereotyped movement disorders

Chihiro Ohba, Masaaki Shiina, Jun Tohyama, Kazuhiro Haginoya, Tally Lerman-Sagie, Nobuhiko Okamoto, Lubov Blumkin, Dorit Lev, Souichi Mukaida, Fumihito Nozaki, Mitsugu Uematsu, Akira Onuma, Hirofumi Kodera, Mitsuko Nakashima, Yoshinori Tsurusaki, Noriko Miyake, Fumiaki Tanaka, Mitsuhiro Kato, Kazuhiro Ogata, Hirotomo SaitsuNaomichi Matsumoto

Research output: Contribution to journalArticlepeer-review

43 Citations (Scopus)

Abstract

Objective Recently, de novo mutations in GRIN1 have been identified in patients with nonsyndromic intellectual disability and epileptic encephalopathy. Whole exome sequencing (WES) analysis of patients with genetically unsolved epileptic encephalopathies identified four patients with GRIN1 mutations, allowing us to investigate the phenotypic spectrum of GRIN1 mutations. Methods Eighty-eight patients with unclassified early onset epileptic encephalopathies (EOEEs) with an age of onset <1 year were analyzed by WES. The effect of mutations on N-methyl-d-aspartate (NMDA) receptors was examined by mapping altered amino acids onto three-dimensional models. Results We identified four de novo missense GRIN1 mutations in 4 of 88 patients with unclassified EOEEs. In these four patients, initial symptoms appeared within 3 months of birth, including hyperkinetic movements in two patients (2/4, 50%), and seizures in two patients (2/4, 50%). Involuntary movements, severe developmental delay, and intellectual disability were recognized in all four patients. In addition, abnormal eye movements resembling oculogyric crises and stereotypic hand movements were observed in two and three patients, respectively. All the four patients exhibited only nonspecific focal and diffuse epileptiform abnormality, and never showed suppression-burst or hypsarrhythmia during infancy. A de novo mosaic mutation (c.1923G>A) with a mutant allele frequency of 16% (in DNA of blood leukocytes) was detected in one patient. Three mutations were located in the transmembrane domain (3/4, 75%), and one in the extracellular loop near transmembrane helix 1. All the mutations were predicted to impair the function of the NMDA receptor. Significance Clinical features of de novo GRIN1 mutations include infantile involuntary movements, seizures, and hand stereotypies, suggesting that GRIN1 mutations cause encephalopathy resulting in seizures and movement disorders.

Original languageEnglish
Pages (from-to)841-848
Number of pages8
JournalEpilepsia
Volume56
Issue number6
DOIs
Publication statusPublished - 2015 Jun 1

Keywords

  • Encephalopathy
  • GRIN1
  • Movement disorders
  • Neurotransmitter disorders
  • Seizure

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology

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