Independent origin for m.3243A>G mitochondrial mutation in three Venezuelan cases of MELAS syndrome

Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a multisystem and progressive neurodegenerative mitochondrial disease, caused by point nucleotide changes in the mtDNA where 80 % of cases have the mutation m.3243A>G in the MT-TL1 gene. In this work, we described the clinical, biochemical and molecular analysis of three Venezuelan patients affected with MELAS syndrome. All cases showed lactic acidosis, cortical cerebral atrophy on magnetic resonance imaging and muscular system deficit, and in two of the cases alteration of urine organic acid levels was also registered. A screening for the mutation m.3243A>G in different patients' body samples confirmed the presence of this mutation with variable degrees of heteroplasmy (blood = 7-41 %, buccal mucosa = 14-53 %, urine = 58-94 %). The mitochondrial haplogroups for the three patients were different (H, C1b, and A2), indicating an independent origin for the mutation.

Automated summary

Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a progressive neurodegenerative mitochondrial disease caused by nucleotide changes in the mtDNA, with the m.3243A>G mutation being the most common. This study analyzed three Venezuelan patients with MELAS syndrome and found common symptoms of lactic acidosis, cerebral atrophy, and muscular system deficit. The mutation m.3243A>G was confirmed in different body samples with varying degrees of heteroplasmy, indicating independent origins for the mutation among the patients' mitochondrial haplogroups.