Despite their ubiquitous expression, mt-ARS deficiencies predominantly affect the CNS, presenting as leukodystrophies (AARS2, DARS2, EARS2, and occasionally LARS2), Leigh syndrome (MARS2, PARS2, NARS2, IARS2), sensorineural hearing loss with ovarian failure (LARS2, HARS2), epilepsy (VARS2, FARS2, RARS2, CARS2), and extrapyramidal syndromes (WARS2, CARS2) (2, 16, 17). The gene discussed is FARS2; the disease is Leigh syndrome.