Objective To delineate the characteristics of the clinical manifestation,pathology of skeletal muscle and gene mutations of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episode (MELAS) in children.Method The clinical manifestation,laboratorial data,brain images,muscle pathology and mitochondrial gene mutations were analyzed in 24 patients with MELAS who were diagnosed in Department of Pediatrics,Peking University First Hospital.Their prognosis was evaluated by following up.Result Symptoms of central nervous system such as stroke-like episodes,vomiting,convulsion and headache were present in all the 24 cases.Nine cases had the symptoms of myopathy.Twenty cases had developmental delay.Short stature,being thin and hairy was very common in these cases.Serum lactate level increased in all the cases,pyruvate increased in 17 cases.Elevated CSF lactate was found in 2 cases.Magnetic resonance imaging (MRI) was performed on 24 cases,out of them 23 were abnormal.The lesions mainly involved cerebral lobes.Occipital lobe was the most common site of lesions.Computed tomography (CT) was performed on 13 cases,low density lesions were present in 10 cases,basal ganglia calcifications in 5 cases.Muscle biopsy was performed on 8 cases,ragged-red fibers (RRF) were found in 4/8 cases,and abnormal accumulation of mitochondria were found in 3/8 cases.The mtDNA gene mutational analysis showed A3243 G mutation in these patients.The mutation rates varied from 11.6％ to 75.0％.The same mutation were found in 4/5 mothers who had the genetic tests,and the mutation rates of the mothers varied from 15.0％ to 23.6％The clinical information of 11 cases was available through recent following up.Three cases died,the others had some degrees of mental retardation.Conclusion Children with MELAS had various clinical manifestations.Central nervous system and skeletal muscle were usually involved.Short stature and hypertrichosis were cormnon signs.The prognosis of this disease was disappointing,mtDNA A3243G was the most common mutation in MELAS.Fully understanding the characteristics of its clinical manifestation,laboratory tests,brain image,muscle pathology and molecular features can be helpful to the early diagnosis and treatment.%目的 探讨儿童线粒体脑肌病伴乳酸酸中毒和卒中样发作(MELAS)的临床、病理以及分子生物学特点.方法 对经基因突变分析确诊为MELAS的24例患儿的临床表现、生化、头颅影像学、肌肉病理及基因突变等特点进行总结,并对其临床转归进行随访.结果 所有患儿均有中枢神经系统受累,主要表现为卒中样发作、呕吐、惊厥、头痛；9例有肌肉受累表现；20例体格发育落后,身材矮小,17例消瘦多毛.24例患儿均有血清乳酸升高,17例血清丙酮酸升高.23例患儿头颅MRI异常,累及多个脑叶,以枕叶受累最为常见(17例)；13例行头颅CT检查,10例见低密度病灶,5例有基底节钙化.8例肌活检,4例见破碎样红纤维,3例有异常线粒体堆积.24例患儿均有线粒体DNAA3243G突变,突变率为11.6％ ～ 75.0％.5例母亲进行了基因突变分析,发现4例有相同突变,突变率15.0％～ 23.6％.随访11例,3例死亡,余者有不同程度的智力低下.结论 儿童MELAS临床表现复杂多样,身材矮小、多毛为其常见体征,线粒体DNA A3243G突变最为常见,预后不良.充分认识其临床、实验室检查、头颅影像学、肌肉病理及基因突变特点,有助于早期诊断和治疗.
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