线粒体呼吸链复合物Ⅰ缺陷导致幼儿肝内胆汁淤积症

线粒体呼吸链复合物缺陷是导致儿童线粒体病的主要原因。本文就1例线粒体呼吸链复合物Ⅰ缺陷导致的幼儿胆汁淤积症患者的临床经过、生化特点、线粒体呼吸链复合物活性分析及基因突变进行回顾性研究。患儿,男,自1岁1个月起腹泻,体重下降,伴无力、进行性黄疸、肝损害。经多种检查、尿液有机酸分析及血液氨基酸、酯酰肉碱谱分析未见特异性改变。外周血白细胞线粒体呼吸链复合物Ⅰ活性降低,线粒体基因分析发现患儿及其母亲tRNA 5821G>A突变,证实患儿存在线粒体呼吸链复合物Ⅰ缺陷。患儿疾病进展迅速,治疗无效,于1岁5个月时夭折。复合物Ⅰ缺陷是线粒体呼吸链缺陷中最常见的类型,本研究首次诊断了1例线粒体呼吸链复合物Ⅰ缺陷所导致的中国儿童患者,其临床表现为胆汁淤积症。线粒体肝病是导致儿童代谢性肝病的主要原因之一,生化分析、线粒体呼吸链复合物活性测定及基因分析是病因诊断的关键。     

线粒体tRNAser(UCN)基因突变致线粒体脑肌病1例并文献复习

目的分析1例线粒体细胞病患儿的临床表现及其基因突变特点。方法对1例临床诊断为线粒体脑肌病患儿归纳总结其临床表现及实验室检查结果，并运用PCR法扩增患儿外周血线粒体基因3243、8344和8993热点突变及已报道的62个常见突变位点所在片段，对扩增片段采用直接测序方法检测突变。在某医院年度体检中选择70名无血缘关系的健康成人作为正常对照，采用PCR RFLP方法进行多态性分析。结果 男性患儿，1岁9个月时出现持续高乳酸血症、反复严重代谢性酸中毒和高氨血症，头颅CT扫描显示双侧额顶叶对称性空泡样低密度灶，考虑线粒体性脑肌病；脑萎缩。2岁时死亡。患儿外周血线粒体基因3243、8344和8993热点突变及已报道的62个常见突变位点均未见突变，患儿线粒体tRNAser(UCN)基因存在7496 T→C突变。为证实在正常人群中线粒体tRNAser(UCN)基因是否存在7496 T→C突变，70名正常对照组皆未发现这一位点突变。结论线粒体脑肌病可以表现为代谢紊乱和神经损伤，应提高警惕。线粒体tRNAser(UCN)基因7496 T→C突变可能导致线粒体细胞病。该突变尚未见报道。     

线粒体呼吸链复合物Ⅱ缺陷与疾病

本文就近年关于线粒体呼吸链复合物Ⅱ的结构、功能及其缺陷的临床表型、诊断、治疗及分子遗传学研究方面的进展进行文献综述。线粒体呼吸链复合物Ⅱ亦称琥珀酸泛醌氧化还原酶,是线粒体呼吸链的重要组分之一,对细胞的氧化磷酸化起着关键作用。呼吸链复合物Ⅱ与氧化性应激密切相关,是细胞内毒性物质以及异常代谢产物的敏感靶标。复合物Ⅱ缺陷导致的线粒体病临床表现多样,以神经肌肉进行性损害为主要表现,少数表现为心肌病、发作性呕吐、溶血尿毒综合征等。诊断有赖于线粒体呼吸链酶复合物活性测定和基因分析。患者受累组织的呼吸链复合物Ⅱ活性降低。已发现SDHA基因与编码复合物Ⅱ组装因子的SDHAF1基因的突变可导致复合物Ⅱ缺陷。目前线粒体呼吸链复合物Ⅱ缺陷的治疗主要是以改善线粒体功能为主。     

ND3基因10191T>C突变导致的线粒体呼吸链复合物Ⅰ缺陷

本文报道1例由于ND3基因突变导致线粒体呼吸链复合物 Ⅰ 缺陷的患儿。该患儿自6岁起出现眼睑下垂、无力、癫癎及运动倒退,呈进行性加重。血液乳酸、丙酮酸增高,脑MRI示双侧基底节对称性损害,符合Leigh综合征诊断。为明确病因,提取患儿和父母的外周血白细胞线粒体蛋白,进行氧化磷酸化酶复合物 Ⅰ～V活性测定,并提取DNA,分析编码线粒体呼吸链复合物 Ⅰ 的7个线粒体结构基因。结果显示患儿线粒体呼吸链复合物 Ⅰ 活性为33.1 nmol/min?毫克线粒体总蛋白（正常对照44.0±5.4 nmol/min?毫克线粒体总蛋白）,复合物 Ⅰ 与柠檬酸合酶活性比值为19.8%（正常对照48.1%±11.0%）,均降低。复合物 Ⅱ～V活性正常。患儿线粒体ND3基因10191T>C突变。其父母线粒体基因及呼吸链复合物酶活性正常。治疗后,现患者16岁,癫癎控制良好,双下肢痉挛性瘫痪,智力正常。通过外周血白细胞线粒体氧化磷酸化酶复合物活性测定及基因分析,本研究首次诊断了编码线粒体呼吸链复合物Ⅰ亚基的ND3基因10191T>C突变导致复合物Ⅰ缺陷,为Leigh综合征的发病原因提供依据。     

线粒体呼吸链复合物Ⅲ缺陷五例的临床特点与生化分析

目的 对5例线粒体呼吸链复合物Ⅲ缺陷患儿进行临床特点和生化分析.方法 对5例患儿(男3例,女2例)临床特点进行归纳总结,并抽取患儿静脉血,分取白细胞线粒体蛋白,采用分光光度测定法检测线粒体呼吸链复合物Ⅰ～Ⅴ活性.结果 (1)5例分别于1个月～15岁时来院就诊.其中3例临床表型符合Leigh综合征,主要表现为智力运动发育落后,运动倒退.l例表现为肝损害,胆汁淤积症.l例表现为进行性肌无力.(2)线粒体呼吸链复合物Ⅰ+Ⅲ活性为3.0～14.2 nmoL/(min·mg线粒体总蛋白),200名正常对照为84.4±28.5 nmol/( min·mg线粒体总蛋白),患儿酶活性降低至正常对照的10.4％～49.3％;复合物Ⅰ+Ⅲ与柠檬酸合酶活性比值为3.5％～22.9％,显著低于正常对照[(66.1±l4.7)％],复合物Ⅰ、Ⅱ、Ⅳ和Ⅴ活性正常,符合单纯线粒体呼吸链复合物Ⅲ缺陷诊断.结论 线粒体呼吸链复合物Ⅲ缺陷病临床表现复杂多样,累及多个系统;复合物Ⅰ+Ⅲ活性以及与柠檬酸合酶活性比值均低于正常对照,而所有患儿复合物Ⅰ、Ⅱ、Ⅳ和Ⅴ活性均未发现异常.     

线粒体MT-TE基因突变致可逆性婴幼儿呼吸链缺乏症1例并文献复习

目的探讨线粒体MT-TE基因突变致可逆性婴幼儿呼吸链缺乏症的临床表现及基因突变特点。方法回顾分析1例确诊为可逆性婴幼儿呼吸链缺乏症患儿的临床资料,并复习相关文献。结果男性患儿,2个月23天,入院时消瘦,呼吸急促,双肺可闻及痰鸣音及喘鸣音;肌力IV级,肌张力减弱。有一胞姐生后不久因重症肺炎去世。入院时肌酸激酶同工酶123 U/L,肌酸激酶890 U/L;血乳酸8.9 mmol/L;病原学检查均为阴性。头颅MRI无异常。入院后患儿持续高乳酸血症、肌酶异常升高,伴呼吸困难,放弃治疗后死亡。基因检查示线粒体MT-TE基因存在14674TC突变,来源于母亲。国外文献报道线粒体MT-TE 14674TC突变患儿早期临床表现与进展型线粒体病类似,呼吸肌无力、喂养困难,运动发育里程碑延迟,肌酶及乳酸升高。予补充能量,维持内环境稳定等治疗,约1岁左右逐渐好转。结论线粒体MT-TE基因突变致可逆性婴幼儿呼吸链缺乏症早期表现与进展型线粒体病类似,积极治疗预后良好。早期进行基因检测可明确预后,增强治疗的信心。     

线粒体神经胃肠型脑肌病的诊治进展北大核心CSCD

线粒体神经胃肠型脑肌病(MNGIE)是一种罕见的常染色体隐性遗传病,发病年龄广泛,从新生儿到50岁均可发病,表现为多系统疾病。现就MNGIE的遗传学特点、临床表型、诊断及治疗的研究进展进行综述,以提高临床医师对该病的认识。     

线粒体呼吸链复合物Ⅱ缺陷所致Leigh综合征

线粒体呼吸链复合物Ⅱ缺陷是较为少见的氧化磷酸化障碍性疾病。本文对1例单纯线粒体呼吸链复合物Ⅱ缺陷所致Leigh综合征患儿的诊疗进行回顾性分析。患儿,男,10个月,8个月时出现发热,热退后出现进行性全身无力、运动发育倒退和吞咽困难。血乳酸、丙酮酸增高,脑MRI显示双侧基底节对称性损害。对患儿进行了外周血白细胞线粒体氧化磷酸化酶复合物I-V活性测定和线粒体基因突变位点筛查分析。线粒体呼吸链复合物Ⅱ活性为21.9 nmol/min?mg线粒体总蛋白（正常对照47.3±5.3 nmol/min?mg线粒体总蛋白）,柠檬酸合酶活性为22.1%（正常对照50.9%±10.7%）,均显著降低。线粒体基因分析未发现异常。患儿确诊为线粒体呼吸链复合物Ⅱ缺陷所致Leigh综合征。经治疗患儿运动功能明显恢复。目前患儿22个月,病情稳定。     

儿童线粒体脑病的临床和分子遗传学特点及其预后

目的探讨儿童线粒体脑病临床及分子遗传学特点和预后。方法对中国人民解放军总医院儿科2008—2013年收治的儿童线粒体脑病11例患儿临床表现、一般实验室检查、肌肉病理及线粒体基因点检测结果进行分析并随访。结果患儿发病年龄6个月~12岁,病程2个月~3年,其中线粒体脑肌病伴乳酸酸中毒和卒中样发作(MELAS)型6例,其他呼吸链酶缺陷引起的线粒体疾病5例。主要表现为抽搐、呕吐、头痛、智力低下、偏瘫等;10例患儿有乳酸升高,其中7例伴丙酮酸升高;6例脑电图示背景慢波增多;头颅磁共振显示受累部位依次为:双侧基底节2例、颞顶枕叶3例、脑内多发病变2例、额顶枕叶1例、顶枕1例、丘脑中脑1例;其中3例行磁共振血管成像(MRA)检查,2例正常,1例左大脑中后动脉分支较对侧少;磁共振波谱分析(MRS)乳酸高峰者3例。2例患儿行骨骼肌病理检查,1例接受骨骼肌病理检查显示异常线粒体堆积。线粒体呼吸链复合物(I~V)缺陷结果复合物Ⅳ缺陷2例,Ⅴ缺陷1例,联合复合物缺陷Ⅰ+Ⅲ缺陷2例。5例白细胞线粒体DNA发现不同位点突变,分别为T8993G、T8993C突变、A3243G突变和11777突变。结论儿童线粒体脑病临床表现多样,实验室检查、头颅影像、基因突变及呼吸链酶学检查有助于早期诊断和治疗,该病预后不佳。     

小儿线粒体性脑肌病4例报告

目的研究小儿线粒体性脑肌病临床特点及其诊断标准。方法总结临床特点,检测血清乳酸及丙酮酸水平,行肌电图、ＣＴ脑扫描、肌活检组织化学染色及电子显微镜超微结构检查。结果４例患儿表现为肌无力,肌萎缩,眼外肌麻痹,身材矮小,癫痫,进行性智力、听力和视力障碍。实验室检查示血乳酸水平升高。肌电图示肌病特点。脑ＣＴ见脑萎缩及基底节对称性钙化。肌活检改良Ｇｏｍｏｒｉ三色染色可见蓬松红纤维。电子显微镜可见形态结构异常的巨大线粒体,部分线粒体内含结晶样包涵体。本文对临床特点、诊断标准、治疗及预后进行了讨论。结论小儿线粒体脑肌病罕见,临床特点及肌肉病理检查是诊断本病的重要根据。     

Intractable secretory diarrhea in a Japanese boy with mitochondrial respiratory chain complex I deficiency

The etiology of secretory diarrhea in early life is often unclear. We report a Japanese boy who survived until 3 years of age, despite intractable diarrhea commencing soon after birth. The fecal sodium content was strikingly high (109 mmol/L [normal range, 27–35 mmol/L]) and the osmotic gap was decreased (15 mOsm/kg), consistent with the findings of congenital sodium diarrhea. We examined the mitochondrial respiratory chain function by blue native polyacrylamide gel electrophoresis (BN-PAGE) in-gel enzyme staining, BN-PAGE western blotting, respiratory chain enzyme activity assay, and immunohistochemistry. Liver respiratory chain complex (Co) I activity was undetectable, while other respiratory chain complex activities were increased (Co II, 138%; Co III, 153%; Co IV, 126% versus respective control activities). Liver BN-PAGE in-gel enzyme staining and western blotting showed an extremely weak complex I band, while immunohistochemistry showed extremely weak staining for the 30-kDa subunit of complex I, but normal staining for the 70-kDa subunit of complex II. The patient was, therefore, diagnosed with complex I deficiency. The overall complex I activity of the jejunum was substantially decreased (63% of the control activity). The immunohistochemistry displayed apparently decreased staining of the 30-kDa complex I subunit, together with a slightly enhanced staining of the 70-kDa complex II subunit in intestinal epithelial cells. These data imply that intestinal epithelial cells are also complex I-deficient in this patient. Complex I deficiency is a novel cause of secretory diarrhea and may act via disrupting the supply of adenosine triphosphate (ATP) needed for the maintenance of ion gradients across membranes.     

End-stage liver disease as the only consequence of a mitochondrial respiratory chain deficiency: no contra-indication for liver transplantation

The prerequisite for liver transplantation as a therapeutic option for inherited metabolic diseases should be that the enzyme defect, being responsible for the major clinical (hepatic and/or extra-hepatic) abnormalities, is localised in the liver. Furthermore, no adequate dietary or pharmacological treatment should be available or such treatment should have an unacceptable influence on the quality of life. We report an infant, who developed end-stage liver disease with persistent lactic acidaemia in his first months of life. Analysis of the mitochondrial respiratory chain in liver tissue revealed a combined partial complex I and IV deficiency. No extra-hepatic involvement could be demonstrated by careful screening for multiple organ involvement, including analysis of the mitochondrial respiratory chain in muscle tissue and cultured skin fibroblasts. The boy received a reduced size liver graft at the age of 8 months. He recovered successfully. Almost 5 years after transplantation he is in good clinical condition. No clinical or biochemical signs of any organ dysfunction have been demonstrated. The considerations on which basis it was decided that there was no contra-indication to perform liver transplantation in this patient are discussed. Conclusion The possibility of a mitochondrial respiratory chain deficiency should be considered in liver disease of unknown origin prior to liver transplantation. Liver transplantation is a therapeutic option in mitochondrial respiratory chain deficiency-based end-stage liver disease provided that extra-hepatic involvement is carefully excluded. Received: 12 October 1999 and in revised form: 26 January 2000 / Accepted: 26 January 2000     

Clinical Presentations of Mitochondrial Cardiomyopathies

To determine the clinical manifestations and interfamilial variability of patients diagnosed with a mitochondrial cardiomyopathy, we reviewed the charts of 14 patients with cardiomyopathy out of 59 patients with mitochondrial disorders who attended the mitochondrial disease clinic at Wolfson Medical Center from 1996 to 2001. All patients underwent a metabolic evaluation including blood lactate, pyruvate, carnitine, and amino acids and urine organic acids. Respiratory chain enzymes were assessed in 10 patients. The mitochondrial DNA (mtDNA) was assessed for mutations.The age at presentation ranged between 6 months and 24 years. Six of the patients died, 5 from heart failure. The cardiomyopathy was hypertrophic in 10 and dilated in 4. Conduction and rhythm abnormalities were present in 6. Eleven patients had family members with mitochondrial disorders. All the patients had additional involvement of one or more systems. Seven patients exhibited a deficiency of a respiratory chain enzyme in the muscle. The MELAS mtDNA point mutation (3243) was found in one patient. Blood lactic acid levels were increased in 5. Brain MRI abnormalities were observed in 4.Conclusions Mitochondrial dysfunction frequently affects the heart and may cause both hypertrophic and dilated cardiomyopathy. The cardiomyopathy is usually a part of a multisystem involvement and may rarely be isolated. The course may be stable for many years, but rapid deterioration may occur. Understanding the biochemical and genetic features of these diseases will enable us to comprehend the clinical heterogeneity of these disorders.     

Mitochondrial respiratory chain complex IV deficiency complicated with chronic intestinal pseudo‐obstruction in a neonate

A female infant born at 36 weeks gestational age with birthweight 2135 g, and who developed respiratory disorder, hyperlactacidemia and hypertrophic cardiomyopathy after birth, was admitted to hospital at 3 days of age. After admission, bilious emesis, abdominal distention, and passage disorder of the gastrointestinal tract were resistant to various drugs. Exploratory laparotomy was performed at 93 days of age, but no organic lesions were identified and normal Meissner/Auerbach nerve plexus was confirmed, which led to a clinical diagnosis of chronic intestinal pseudo‐obstruction (CIPO). She was diagnosed with mitochondrial respiratory chain complex IV deficiency on histopathology of the abdominal rectus muscle and enzyme activity measurement. This is the first report of a neonate with mitochondrial respiratory chain complex deficiency with intractable CIPO. CIPO can occur in neonates with mitochondrial respiratory chain disorder, necessitating differential diagnosis from Hirschsprung disease.     

Leigh Disease due to deficiency of mitochondrial respiratory chain complexes I, III and IV

Leigh disease is a clinically heterogeneous and infrequent disorder in the pediatric age group. Inheritance is variable. It results from a genetic defect producing deficiencies in enzyme complexes and functional disturbance of the mitochondria. The prognosis is poor and effective treatment is lacking. We present the case of a 1-month-old boy with early manifestation and rapid progression of Leigh disease due to deficiency of mitochondrial respiratory chain complexes I, III and IV.