TRIT1 defect leads to a recognizable phenotype of myoclonic epilepsy, speech delay, strabismus, progressive spasticity, and normal lactate levels

J Inherit Metab Dis. 2022 Nov;45(6):1039-1047. doi: 10.1002/jimd.12550. Epub 2022 Sep 21.


TRIT1 defect is a rare, autosomal-recessive disorder of transcription, initially described as a condition with developmental delay, myoclonic seizures, and abnormal mitochondrial function. Currently, only 13 patients have been reported. We reviewed the genetic, clinical, and metabolic aspects of the disease in all known patients, including two novel, unrelated TRIT1 cases with abnormalities in oxidative phosphorylation complexes I and IV in fibroblasts. Taken together the features of all 15 patients, TRIT1 defect could be identified as a potentially recognizable syndrome including myoclonic epilepsy, speech delay, strabismus, progressive spasticity, and variable microcephaly, with normal lactate levels. Half of the patients had oxidative phosphorylation complex measurements and had multiple complex abnormalities.

Keywords: OXPHOS; lipidomics; mitochondrial tRNA; myoclonic seizures; spasticity.

Publication types

  • Review
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkyl and Aryl Transferases* / genetics
  • Epilepsies, Myoclonic* / genetics
  • Humans
  • Lactates
  • Language Development Disorders*
  • Muscle Spasticity
  • Phenotype
  • Strabismus*


  • Lactates
  • TRIT1 protein, human
  • Alkyl and Aryl Transferases