Clinical Manifestation, Image, Electroencephalogram And Genetic Study In MELAS Syndrom

Objective The aim of this research is to explore the clinical symptoms,radiological imaging, electroencephalogram(EEG) evidence and gene mutation of mitochondrial myopathy, encephalopathy,lactic acidosis,and stroke-like episodes(MELAS) syndrom. Simultaneously,to test the mutations in blood and urine,confirm a reasonable specimens for gene test and support the noninvasive gene tests.Methods The main research objects were suspected or confirmed mitochondrial encephalomyopathy cases.Firstly,mt DNA were extracted from blood and urine of all patients collected.Then,the mt DNA mutation in urine and blood were tested by polymerase chain reaction and restriction enzyme reaction(preselected,A3243G/A8344G/T8993C/T8993G/G13513A).Finally,the mutational load of mt DNA were calculaed.Image and EEG results were collected from the confirmed cases.Results Twelve patients were confirmed with a average onset age of twenty-eight.Of all the cases,66.7% had epilepsy,50% had stroke-like episodes,41.7%had mental behavious dissorder and descent of memory and perceive,41.7% had diabetes or abnormal glucose tolerance,41.7% had hearing impairment,16.7% had migraine,16.7% had hallucination,8.3% had muscular fatigue,and one case was asymptomatic carriers.There were eight patients with A3243 G heterozygous mutation and confirmed with mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes(MELAS).The mutational load of these eight patients in blood and urine were 17.80% and 60.16%、20.88% and 73.96%、29.62% and 92.58%、36.01% and91.29%、5.14% and 48.78%、5.74% and 58.57%、0.57% and 5.99%,5.59% and45.37%,respectively.The magnetic resonance imaging(MRI) showed six casses had bilateral cerebral hemisphere involved while three had unilateral,three cases had basal nuclei abnormal signal,one case implicated cerebellum,five cases had encephalatrophy in various degrees.Magnetic resonance angiography(MRA) showed no abnormal sign.Sixpatients had magnetic resonance spectroscopic(MRS) imaging,five showed large lactate peak at 1.33 ppm and five displayed descreased NAA peak.Eight of the confirmed paitents with epilepsy had EEG examination.The result showed four with generalized slowing,two with epileptiform discharges,two without abnormal.None showed epileptic seizures during examination.Conclusion The clinical symptoms of MELAS syndrom is highly variable,and no obvious specificity on MRI and EEG,MRS showed large lactate peak may support diagnosis of disease,but gene detection is gold standard.Urine is easy to obtain and the mutation load in urine is greater than in blood,so urine should be the preferred specimens for gene detection.