线粒体肌病和脑肌病患者骨骼肌细胞线粒体DNA缺失分析

目的为了检测线粒体肌病和脑肌病患者的骨骼肌细胞的线粒体ＤＮＡ的缺失情况。方法从６例原发性线粒体肌病和１例脑肌病患者的骨骼肌活检标本中，提取总ＤＮＡ，以线粒体ＤＮＡ全长为探针进行分子杂交。结果发现１例ＭＥＲＲＦ患者有５ｋｂ的线粒体ＤＮＡ基因缺失，另１例线粒体肌病患者有１５ｋｂ的线粒体ＤＮＡ基因缺失，剂量分析表明缺失型线粒体ＤＮＡ分别占总线粒体ＤＮＡ的１９．３％和１０．７％。结论线粒体ＤＮＡ基因缺失是线粒体疾病的重要病因之一     

全基因组检测线粒体脑肌病的基因突变研究

目的探讨全基因组检测线粒体脑肌病(ME)基因突变的临床意义。方法分析8例ME的临床特征、24h视频脑电图(VEEG)、肌电图(EMG)、头颅MRI、全基因组检测基因突变。结果 8例全基因组检测基因突变表明,存在核基因突变8例、有氨基酸改变7例、线粒体基因突变8例;其中t RNA基因突变5例、TRNL1基因突变4例、ATP6基因突变3例、ND5和TRNS2基因突变各1例。核酸3243AG改变4例(50%),其他有8860AG,11719GA,14766CT,8993TG等4例(50%),氨基酸改变4例。结论ME患者大多存在核基因的突变,线粒体的5个mt DNA均可发生突变。本组患者核酸改变仅50%发生在3243位点,检测核基因和线粒体基因是诊断ME的依据之一。     

Central nervous system changes in mitochondrial encephalomyopathy: light and electron microscopic study

Summary An autopsy case of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) is reported. It presented with generalized muscle atrophy, stroke-like episodes, schizophrenia-like mental disorder and progressive dementia. Serum lactate and pyruvate levels were high. In the biopsied muscles, ragged-red fibers were observed by light microscopy and aggregation of abnormal mitochondria with paracrystaline formation by electron microscopy. The most characteristic neuropathological findings were infarct-like lesions widespread in the cerebral cortex. In addition, this case showed some unusual pathological features: (1) diffuse moderate fibrillary gliosis in the whole cerebral and cerebellar white matter, which might have been due to metabolic disturbances; (2) several focal lesions with demyelination and numerous spheroids in the pontocerebellar fibers; and (3) marked degeneration of the posterior columns and spinocerebellar tracts. Electron microscopic examination revealed that abnormal mitochondria were markedly aggregated in smooth muscle cells and endothelium of the cerebral and cerebellar blood vessels. These fine structural findings suggest a mitochondrial angiopathy.     

线粒体脑肌病1例诊治经过并文献复习

目的探讨线粒体脑肌病的临床病理特点及误诊原因。方法结合文献对线粒体脑肌病的病理特点及误诊原因进行回顾性分析。结果患者表现为头痛、抽搐、卒中样发作，曾被误诊为癫痫、颅内感染、脉管炎和脑梗死，经乳酸运动试验、肌肉活检和基因检测确诊为线粒体脑肌病（MELAS型）。结论线粒体脑肌病临床表现复杂多样，临床诊断困难，全面掌握线粒体脑肌病的临床病理知识，有助于本病的诊断和治疗。     

线粒体肌病与线粒体脑肌病的临床分析

目的探讨神经肌肉系统线粒体病的发病机制、临床与病理特征及诊断。方法对7例确诊为线粒体病患者的临床表现、病理检查、实验室与影像学资料进行了回顾性分析。结果该组患者诊断为线粒体肌病3例,线粒体脑肌病4例;其中2例患者血乳酸水平升高;7例患者肌电图均有异常发现,肌肉活检均有特征性的改变;4例线粒体脑肌病患者头部影像学均有异常改变。结论线粒体病主要累及肌肉及中枢神经系统,诊断要求多种手段结合,以临床和病理表现为主,近年来基因方面的研究及影像学诊断发展迅速,目前对本病主要采取对症治疗。     

线粒体脑肌病的临床、病理与神经电生理

目的探讨线粒体脑肌病的临床、肌肉病理及神经电生理特点，以便早期诊断。方法对6例确诊的线粒体脑肌病患者的临床表现、肌肉组织光镜和超微结构改变以及神经电生理改变进行了回顾性分析。结果本组患者的临床特征主要以运动不耐受，阵挛、抽搐发作，精神障碍，共济失调为主。6例患者中4例发现破碎红纤维（RRF），其平均比例为5．3％；超微结构观察有线粒体异常及糖原颗粒沉积，其中有2例发现有典型晶格状包涵体。以癫痫发作为主要临床表现的患者脑电图明显异常；肌电图以神经源性改变4例，占本组病例的4／6；听觉诱发电位（BAEP）、体感诱发电位（SEP）异常3例，占3／6。结论线粒体脑肌病的临床表现复杂多样，诊断主要依赖于临床特征分析和肌肉活检；电镜超微结构改变为线粒体病的主要诊断依据；神经电生理改变对病理损伤累及范围和程度方面有一定的参考价值。     

肌阵挛癫痫合并破碎红纤维综合征的线粒体DNA突变特点

目的　探讨肌阵挛癫痫伴破碎红纤维综合征 ( MERRF)的分子遗传学特点。方法　用聚合酶链反应-限制片段长度多态性 ( PCR- RFL P)方法检测 6例 MERRF患者及其部分母系亲属的肌肉和 (或 )外周血细胞的mt DNA的 A8344 G点突变 ,并进行突变型 mt DNA的定量分析。结果　在 2例患者的肌肉和外周血细胞中检测到A8344 G点突变。但其母亲的外周血细胞中未能检测到此突变。这 2例 A8344 G阳性标本中 ,肌肉组织的突变型mt DNA的比例分别为 79.0 %和 86 .8%,而在外周血细胞中分别为 5 9.7%和 72 .9%,突变型 m t DNA的比例在肌肉组织中高于外周血细胞中。结论　在 MERRF患者不同组织中检测到 mt DNA A8344 G点突变 ,与国外报道一致。但国外报道 MERRF多为母系遗传 ,而我们的病例未能有此发现 ,须扩大样本量进一步分析。     

线粒体脑肌病的MR诊断与鉴别诊断:附4例报告并文献复习

目的:探讨线粒体脑肌病(ME)的MR诊断与鉴别诊断。方法:分析4例线粒体脑肌病患者的临床`实验室及MRI表现,其中4例行常规MRI扫描,1例行MRA扫描。结果:3例病变主要累及两侧大脑皮层和皮层下,1例主要表现为白质内改变,均表现为长T1长T2信号,2例合并脑萎缩,MRA示1例未见明显改变。结论:MRI对线粒体脑肌病的脑内病变敏感,当年轻患者出现非典型性脑梗死表现,应考虑到线粒体脑肌病的可能。     

原发性线粒体肌病与脑肌病(附53例报告)

本文报道了原发性线粒体肌病与脑肌病53例,均经肌活检组织化学染色,超微结构检查及生化检测线粒体呼吸链酶复合体Ⅰ—Ⅳ的活性证实。临床类型包括线粒体肌病44例,KSS及CPEO8例,MELAS型1例。实验室检查包括神经电生理,血清肌酶谱,血乳酸、丙酮酸最小运动量试验.肌活检形态学和生化检测,以及线粒体形态计量分析。并对本组疾病的临床特点,各种检查的诊断价值及治疗进行了讨论。     

线粒体脑肌病伴高乳酸血症和卒中样发作患者抑郁的相关因素分析

目的 分析线粒体脑肌病伴高乳酸血症和卒中样发作(MELAS)患者抑郁的相关因素。方法(1)采用抑郁自评量表( SDS)调查32例MELAS患者的抑郁状况;(2)将患者分为抑郁组与非抑郁组,比较2组患者SDS各分项的评分;(3)以性别、发病年龄、受教育年限、病程、MMSE 评分及主要症状作为可能的相关因素进行单因素分析及多因素Logistic回归分析。结果(1)MELAS患者抑郁的总发生率为62.5%,其中轻度抑郁发生率34.4%,中度抑郁18.7%,重度抑郁9.4%;(2)MELAS患者SDS评分显著高于国内常模评分(P<0.01);(3)抑郁组患者SDS 3个分项(精神性-情感症状、精神运动性障碍、抑郁的心理障碍)评分分别显著高于非抑郁组(P<0.05或0.01);(4)抑郁组与非抑郁组之间的病程、胃肠道损害及癫痫例数的比较均有显著差异(P<0.05或0.01);(5)Logistic回归分析显示MELAS患者伴发抑郁与病程、胃肠道损害及癫痫显著相关(P<0.05或0.01)。结论 MELAS患者伴发抑郁不少见,其发生可能与病程、胃肠道损害及癫痫有关。     

TYMP基因新突变型线粒体神经胃肠脑肌病1例报告及文献回顾

目的探讨线粒体神经胃肠脑肌病患者的临床表现及基因突变情况。方法分析1例线粒体神经胃肠脑肌病患者的临床资料。提取外周血单核细胞DNA进行基因测序。结果该患者表现为进行性加重的胃肠道症状、脑白质病、恶液质、周围神经病及眼外肌无力。基因检测发现TYMP基因c.417+1GA纯合变异为该患者的致病突变,该突变为新发突变。结论经基因检测确诊TYMP基因新发突变致线粒体神经胃肠脑肌病。     

Content of mutant mitochondrial DNA and organ dysfunction in a patient with a MELAS subgroup of mitochondrial encephalomyopathies

A point mutation of mitochondrial tRNA^Leu(UUR) gene is responsible for a MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) subgroup of mitochondrial encephalomyopathies. In most cases, the mutant mitochondrial DNA (mtDNA) coexists with normal mtDNA in a heteroplasmic manner. In order to quantify the content of mutant mtDNA, we developed a quantitative method of PCR. Using this method, the distribution of the mutant mtDNA was examined in 32 different tissues among 18 autopsied organs from a patient with MELAS, who had shown hypophyseal dysfunction. The percentage of the mutant mtDNA at nucleotide number 3243 in each tissue was ranged between 22% and 95%. The content of the mutant mtDNA was at the highest (95%) in the hypophysis and higher in the cerebral cortex than in the white matter. This study shows a possible correlation of tissue dysfunction with accumulation of the mutant mtDNA within the brain.     

Mitochondrial DNA depletion in sporadic inclusion body myositis

Sporadic inclusion body myositis (sIBM) is a late onset disorder of unkown aetiology. Mitochondrial changes such as cytochrome oxidase deficient fibres are a well recognised feature and mitochondrial DNA (mtDNA) deletions have also been reported, but not consistently. Since mtDNA deletions are not present in all cases, we investigated whether other types of mtDNA abnormality were responsible for the mitochondrial changes. We studied 9 patients with sIBM. To control for fibre loss or replacement with inflammatory cells, we compared sIBM patients with necrotising myopathy (n?=?4) as well as with healthy controls. Qualitative anlysis for mtDNA deletions and quantitative measurement of mtDNA copy number showed that muscle from patients with sIBM contained on average 67% less mtDNA than healthy controls (P?=?0.001). The level of mtDNA was also significantly depleted in sIBM when compared to necrotising myopathy. No significant difference in copy number was seen in patients with necrotising myopathy compared to controls. Deletions of mtDNA were present in 4 patients with sIBM, but not all. Our findings suggest that mtDNA depletion is a more consistent finding in sIBM, and one that may be implicated in the pathogenesis of the disease.     

MELAS: clinical phenotype and morphological brain abnormalities

We describe the clinical and neuropathological findings of three unrelated autopsy cases of MELAS harboring the A3243G transition in the mitochondrial DNA (mtDNA). Using immunohistochemical techniques, we studied the expression of several subunits of the respiratory chain in various brain regions from the same cases. In all three cases there was a reduced immunocytochemical staining for mtDNA-encoded subunits of the respiratory chain, confirming the presence of a defective mitochondrial protein synthesis in this disease. Mitochondrial abnormalities were mostly confined to multiple areas of different size and shape, in agreement with the focal character of the brain pathology in MELAS, and were most prominent in the cerebral cortex, providing a morphological contribution to the explanation of the cognitive regression of the patients. Immunoreactivity for mtDNA-encoded subunits was reduced in the walls of many pial and intracerebral arterioles of different brain regions but there was no clear correlation between territories of affected vessels and distribution of the histological and immunohistochemical lesions. Cerebral focal lesions in MELAS might have a metabolic nature and several pathogenetic mechanisms might be involved in the genesis of stroke-like episodes when there is a local increased ATP demand.     

An autopsy case of mitochondrial encephalomyopathy with prominent degeneration in olivo-ponto-cerebellar system

Summary We describe a sporadic case of adult-onset, complex I deficiency mitochondrial encephalomyopathy (MEM), the clinical and pathological features of which failed to fit any of the known subgroups of MEM, such as Kearns-Sayre syndrome, mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes or myoclonus epilepsy with ragged-red fibers. Clinically, this patient had only progressive cerebellar ataxia, generalized muscle weakness and hearing loss. The principal finding at autopsy was degeneration of the olivoponto-cerebellar system. This case suggests that mitochondrial disease could underlie some cases of olivoponto-cerebellar atrophy.     

Progressive myofiber loss with extensive fibro-fatty replacement in a child with mitochondrial DNA depletion syndrome and novel thymidine kinase 2 gene mutations

The mitochondrial DNA depletion syndromes (MDS) are autosomal recessive disorders with a decreased mitochondrial DNA copy number. Mutations in thymidine kinase 2 (TK2) have been responsible for the myopathic form of MDS. We describe a child with congenital muscle weakness who had a progressive mitochondrial myopathy associated with extensive fibro-fatty replacement of myofibers resembling muscular dystrophy. MDS was suspected based upon findings in the initial muscle biopsy. Sequence analysis of the TK2 gene revealed two novel heterozygous mutations: the frame shift mutation, c.255_c.258delAGAA, and the heterozygous missense mutation, c.515G>A, (p.R172Q). This report extends the phenotype and genotype of TK2 defects.     

Stroke-like episodes in familial mitochondrial encephalomyopathy: clinical and biochemical aspects

Summary Acute episodes of focal neurological dysfunction are a well-recognized complication of the mitochondrial encephalomyopathies. Because of rapid remission, biochemical tests and other diagnostic procedures are mostly performed after the acute phase. We report the case of a patient suffering from mitochondrial disease manifesting primarily with seizures, progressive deafness and dementia, who experienced multiple stroke-like episodes. Other members of the family with evidence of mitochondrial dysfunction are presented briefly. EEG and biochemical findings in the acute stage are correlated with clinical symptoms, showing characteristics distinct from the chronic illness. The possible involvement of dietary factors in the provocation of stroke-like episodes is discussed and regulation of glucose intake suggested as a strategy in the prevention of stroke-like episodes.     

线粒体脑肌病伴高乳酸血症和卒中样发作综合征的线粒体DNA突变特点

目的 探讨线粒体脑肌病伴高乳酸血症和卒中样发作（MELAS综合征）的分子遗传学特点。方法 用聚合酶链反应-限制片段长度多态性（PCR-RFLP）方法检测来自7个家庭的9例MELAS患者及其部分母系亲属的肌肉和（或）外周血细胞的mtDNA的A3243G和T3271C点突变,并进行突变型mtDNA的定量。结果 在9例患者和1例亲属的肌肉和（或）外周血细胞中检测到A3243G点突变,未检测到T3271C突变。在这10例A3243G阳性标本中,外周血细胞（9例）的突变型mtDNA的比例为26.8%-50.3%;肌肉组织（4例）的突变型mtDNA的比例为46.8%-61.0%;对3例患者同时进行了肌肉和血细胞标本的检测,突变型mtDNA的比例肌肉组织均高于血细胞。对6个家庭的部分母系亲属的血细胞研究表明：只有1例先证者的同胞有此突变;另外3例先证者的母亲及2例先证者的同胞均未检测到此突变。另外有2例先证者的儿子临床表现符合MELAS,血中也检测到此突变。结论 mtDNA A3243G突变在本组MELAS综合征中的发生率较高,并且可在不同组织中检测到此突变,与国外文献报道一致;但国外报道多为母系遗传,而我们的病例以散发的居多,推测是由于新生突变所致。     

Muscle mitochondrial DNA in encephalomyopathy and ragged red fibres: a Southern blot analysis and literature review

Summary Various mitochondrial DNA abnormalities have been described in patients with encephalomyopathies. We performed Southern blot analysis of skeletal muscle mitochondrial DNA in nine adult patients with clinical features and ragged red fibres suggesting mitochondrial dysfunction. Two patients with encephalomyopathy and two with the MERRF syndrome (myoclonus epilepsy with ragged red fibres) had the normal PvuII restriction pattern of muscle mitchondrial DNA. In contrast, mitochondrial DNA deletion was observed in two of six patients with ophthalmoplegia. One suffered from typical Kearns-Sayre syndrome and the other from isolated external ophthalmoplegia. None of these patients had affected relatives. The detection of mitochondrial DNA deletion in external ophthalmoplegia and their site and size support previously reported data.     

Mitochondrial encephalomyopathy,lactic acidosis and stroke in adults: two cases

Two previously healthy women are described who in their late thirties suffered transient strokelike episodes, consisting of initial headache and vomiting, with various subsequent neurological signs that were only partially reversible. Investigations revealed elevated serum creatine kinase, lactic acidosis, hypertriglyceridaemia, and ragged red fibres in the muscle biopsy specimens. In both patients in vitro studies were performed on intact muscle mitochondria and muscle homogenate. Only in one was a mitochondrial defect found, located at the level of coenzyme Q. We conclude that these patients suffered from adult-onset mitochondrial encephalopathy, lactic acidosis and strokelike episodes (MELAS syndrome). Although the syndrome is often associated with long-standing neurological multisystem disease from childhood onwards, it should also be suspected in adults with strokelike signs of otherwise unexplained origin.