Clinical, myopathological and genetic research of a patient with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes/Leigh syndrome overlap syndrome caused by m. 10158 T>C mutation

Objective To report the clinical, myopathological and genetic features of a patient with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS)/Leigh syndrome (LS) overlap syndrome who carried m. 10158 T>C mutation. Methods The patient′s clinical and imaging materials were collected. An open biopsy of right biceps brachii was performed. DNA samples were prepared from the patient and her mother′s blood. Direct sequencing of the complete mitochondrial genome was performed to detect the mtDNA mutation. Western blotting was used to estimate the content of respiratory complexes in the patient′s muscle. Results The patient was a 40-year-old female. She had seizures and lost consciousness for 9 months. Brain MRI findings consisted of asymmetrical lesions in the cerebral cortex of the frontal and temporal lobes, as well as symmetrical lesions bilaterally in the basal ganglia. Muscle biopsy showed typical ragged red fibers. Direct sequencing of the complete mitochondrial genome from blood and muscle of the patient revealed the T-to-C transition at nucleotide position 10158 in the MT-ND3 gene. The mutation rate was 9.31% and 70.0%, respectively. Western blotting demonstrated that the contents of complexes Ⅰ and Ⅳ were significantly lower in the patient′s muscle mitochondria compared with the normal controls (53.1%±1.2% vs 88.6%±1.7%, t=4.08, P<0.05; 57.3%±2.4% vs 80.1%±2.1%, t=3.39, P<0.05). Conclusion We reported a case of MELAS/LS overlap syndrome who carried m. 10158 T>C mutation in MT-ND3 gene and DNA test is very important for the diagnosis of the disease. Key words: MELAS syndrome; DNA, mitochondrial; Mutation; Magnetic resonance imaging; Biopsy