MCAT and MERRF: Myoclonic epilepsy with ragged red fibers (MERRF) is a mitochondrial disorder defined by the presence of progressive myoclonus epilepsy and ragged-red fibers (RRF) observed in muscle biopsies.276 This disease also manifests with symptoms like ataxia, cardiomyopathy, lipomatosis, and dementia.277 In 1990, a significant association was identified between MERRF and the m.8344 A > G point mutation in the MT-TK gene, responsible for encoding mt-tRNALys(UUR).