Six known pathogenic variants in MT-TL1, MT-ATP6 and MT-TK causing Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS), Leigh and Myoclonus epilepsy associated with ragged-red fibers (MERRF) syndromes, respectively, were identified (Table 3). This evidence concerns the gene MCAT and MERRF syndrome.