Mitochondrial myopathy,encephalopathy,lactic acidosis and stroke-like episodes:clinical manifestations and gene mutation analysis

Objective To investigate the characteristic clinical manifestations and gene mutations in mitochondrial myopathy,encephalopathy,lactic acidosis and stroke-like episodes(MELAS).Methods The clinical manifestations,imaging data and muscle pathologies of a patient with MELASwere analyzed,and the mutations in the mitochondrial DNA were investigated using polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP)and gene sequencing.Results MELAS was clinically characterized by such symptoms as recurrent headache and vomiting,stroke-like episodes,epilepsy,intolerance to exercise,short stature,nerve deafness and lactic acidosis.CT scan demonstrated bilateral basal ganglia calcification,and magnetic resonance imaging(MRI)showed abnormal signals in the occipital lobe.Proton magnetic resonance spectroscopy revealed a visible peak of lactic acid in the area with T2-weighted abnormal signals,while a low peak of lactic acid was identified in the area with T2-weighted normal signals.Muscle biopsy did not find any mitochondrial anomalies.A heterozygous A 3243G mutation in the mitochondrial DNA was found in this patient.Conclusion The diagnosis of MELAS relies on a comprehensive analysis of the clinical features,imaging findings,pathological results and genetic analysis.Normal pathological results do not rule out the possibility of MELAS.Mitochondrial DNA mutation analysis should be carried out as a routine procedure for identifying MELAS. Key words: MELAS syndrome; Gene mutation; Gene diagosis