De novo mutation in SLC25A22 gene: expansion of the clinical and electroencephalographic phenotype

J Neurogenet. 2021 Mar-Jun;35(2):67-73. doi: 10.1080/01677063.2021.1892094. Epub 2021 Apr 6.


The SLC25A22 (Solute Carrier Family 25, Member 22) gene encodes for a mitochondrial glutamate/H+ symporter and is involved in the mitochondrial transport of metabolites across the mitochondrial membrane. We hereby report a 12-year-old girl presenting with early-onset epileptic encephalopathy, hypotonia, and global developmental delay. Whole exome sequencing identified a novel homozygous missense mutation in SLC25A22 gene (c.97A>G; p.Lys33Glu), as the likely cause of the disease. The phenotype of our patient and EEG recordings do not completely overlap with the phenotypes previously described, leading to a new and more complex form of disease associated with SLC25A22 variants, characterized by dyskinetic movements and oculogyric crisis.

Keywords: Dyskinetic movements; SLC25A22 gene; epileptic encephalopathy; glutamate; oculogyric crisis.

Publication types

  • Case Reports

MeSH terms

  • Child
  • Developmental Disabilities* / genetics
  • Electroencephalography
  • Epilepsy, Generalized* / genetics
  • Female
  • Humans
  • Mitochondrial Membrane Transport Proteins / genetics*
  • Muscle Hypotonia / genetics
  • Mutation, Missense
  • Phenotype


  • Mitochondrial Membrane Transport Proteins
  • SLC25A22 protein, human