ClinVar

In a 22-year-old woman (trio 91) with developmental and epileptic encephalopathy-33 (DEE33; 616409), de Ligt et al. (2012) identified a de novo heterozygous c.208G-A transition in the EEF1A2 gene, resulting in a gly70-to-ser (G70S) substitution at a highly conserved residue. The patient had neonatal hypotonia and developed seizures at age 4 months. She had severely delayed psychomotor development, with limited speech, autistic features, and aggressive behavior. The patient was ascertained from a larger cohort of 100 patients with severe intellectual disability who underwent exome sequencing. Functional studies of the variant were not performed.

Veeramah et al. (2013) identified a de novo heterozygous G70S substitution in a 14-year-old boy with DEE33. He developed refractory seizures with hypsarrhythmia at age 10 weeks, and later showed severe developmental delay, with episodic regression, acquired microcephaly, hypotonia, incoordination, and gait instability. He was nonverbal. The phenotype was consistent with a clinical diagnosis of West syndrome. The mutation, which was found by whole-exome sequencing, was not present in the 1000 Genomes Project or Exome Sequencing Project databases. The patient was 1 of 10 probands with epileptic encephalopathy who underwent whole-exome sequencing. Functional studies of the variant were not performed.