In addition, one individual demonstrated heteroplasmy for MTTL1 3243 A > G (estimated 58% frequency in blood) which is the most common mtDNA mutation associated with Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like episodes (MELAS, MIM 540000). This evidence concerns the gene MT-TL1 and mitochondrial encephalomyopathy.