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。     

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。     

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.     

线粒体呼吸链酶复合物V缺陷与线粒体病

线粒体呼吸链酶复合物V,也称为ATP合酶,是位于线粒体内膜上的大蛋白复合体,由2个功能性蛋白复合物F0及F1构成。复合物V是线粒体呼吸链的最后一个复合物,在线粒体中通过电化学梯度传递质子,以ADP、Pi及Mg2+为原料合成ATP,为细胞供能。大多数患者新生儿期发病,导致严重脑损害或多脏器损害,病死率很高。主要临床表现为神经肌肉病、心肌病、高乳酸血症及3 甲基戊烯二酸尿症等,因受累器官的不同导致显著的临床异质性。复合物V由16个亚基组成,由线粒体基因与核基因共同编码。迄今,国内外已报道了MT-ATP6、MT-ATP8、ATPAF2、TMEM70、ATP5E基因突变导致的复合物V缺陷。本文总结了线粒体呼吸链复合物V的结构及功能,并对复合物V缺陷的病理、临床表现、诊断、治疗及分子遗传学研究进展进行了综述。     

Disorders of the mitochondrial respiratory chain: clinical manifestations and diagnostic approach

The clinical identification of patients with defects in the mitochondrial respiratory chain is almost impossible. We describe screening tests that should be performed in order to select those patients in whom a skeletal muscle biopsy should be carried out for more specific biochemical assays. The importance of performing in vivo function tests is stressed. The biochemical diagnosis in disorders of the respiratory chain is presented and the application of immunological methods discussed.Abbreviations ATP adenosine triphosphate - CoA coenzyme A - DCPIP 2,6-dichlorophenol indophenol - KCN potassium cyanide - NAD⁺ nicotinamide adenine dinucleotide (oxidized) - NADH nicotinamide adenine dinucleotide (reduced) - PMS phenazine methosulfate     

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。     

A mitochondrial myopathy with a defective respiratory chain and carnitine deficiency

A boy presented suffering from generalised weakness, exercise intolerance and lactic acidosis. The weakness became evident at 2 years. A cerebral CT-scan showed cerebellar atrophy and central and peripheral atrophy of both hemispheres. With trichrome staining about 20% of the muscle fibres showed large areas containing redstaining granular material. Electron microscopic examination showed that this material consisted of areas of mitochondrial proliferation, most of the mitochondria having abnormal ultrastructural characteristics. Pyruvate dehydrogenase complex and citric acid cycle activities were determined by measuring ¹⁴CO₂ production from various labelled substrates. Diminished oxidation rates were found with the patient's muscle homogenate for all substrates tested, indicating a defect in the respiratory chain. The cytochromes were present in normal quantities. Succinate cytochrome c reductase activity was very decreased. Carnitine concentration was decreased in serum and in muscle as well.     

线粒体基因13513G>A突变导致呼吸链酶复合物I缺陷Leigh综合征

Leigh综合征是由于线粒体呼吸链能量代谢障碍所导致的遗传性疾病,呼吸链酶复合物I缺陷是导致Leigh综合征的常见原因之一。该研究通过线粒体基因13513G>A突变分析首次确诊了1例中国人Leigh综合征患者。患儿为第一胎,12岁时出现抽搐,13岁时先后出现双眼视力下降,13岁来院就诊左眼颞侧视野缺损,痉挛步态,血液乳酸、丙酮酸增高,腓肠肌活检肌纤维内脂滴轻度增多;心电图检查显示不完全右束支传导阻滞;脑MRI显示双侧基底节对称性损害,符合Leigh综合征诊断,合并继发性癫癎。经基因分析证实患者存在线粒体基因13513G>A突变,导致线粒体呼吸链酶复合物I活性下降。治疗以多种维生素为主,补充左旋肉碱、辅酶Q10,同时给予卡马西平、苯巴比妥、丙戊酸等抗癫癎治疗。现在患儿16岁,休学,智力无明显倒退,体力、体重显著减退。Leigh综合征病因复杂,临床表现多种多样,该患儿以抽搐起病,合并视力减退,经基因分析明确了病因,有助于相关家庭的遗传咨询 。［中国当代儿科杂志,2009,11（5）：333-336］     

Combined deficiencies of the pyruvate dehydrogenase complex and enzymes of the respiratory chain in mitochondrial myopathies

In six patients with mitochondrial (encephalo-) myopathy investigations of skeletal muscle revealed a defect of pyruvate dehydrogenase complex (PDHC) in combination with one or more respiratory chain complex deficiencies. A combination of defects of this kind has not been reported previously. Five of the six patients presented within the 1st year of life and had a severe clinical course. Intrafamilial variability of the clinical course in dizygotic twins both suffering from a cytochrome c oxidase deficiency and one of them also from a PDHC deficiency suggests an additional effect of PDHC deficiency on the clinical symptoms. Immunoblot studies of PDHC in five of the patients revealed no abnormalities in their subunit pattern, rendering a defect of mitochondrial protein import or assembly unlikely. The finding of a combined PDHC and respiratory chain deficiency has implications for the diagnostic approach, for therapy and genetic counselling. The exact pathogenetic mechanism of this combination of defects remains to be elucidated.     

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     

线粒体呼吸链酶复合物Ⅰ缺陷的临床和分子遗传学研究进展

线粒体病病因复杂,基本原因为线粒体呼吸链酶系统代谢异常导致氧化磷酸化障碍,三磷酸腺苷(ATP)产生减少,因此,能量需求越高的组织和器官受损越重,如中枢神经系统、骨骼肌和心脏[1-2].     

Mitochondrial respiratory chain complex I deficiency causes intractable gastrointestinal symptoms

We report the case of a 13‐month‐old girl with frequent vomiting, intractable diarrhea, hyperlactatemia, and liver dysfunction. Although the symptoms were treatment resistant, enteral nutrition formula containing medium‐chain triglycerides reduced the weight loss, vomiting, and diarrhea. Immunostaining of mitochondrial respiratory chain (MRC) complexes of the colonic mucosa confirmed the diagnosis of MRC complex I deficiency. This case shows that this disease should be included in the differential diagnosis of hyperlactatemia and intractable, cryptogenic gastrointestinal symptoms. In addition, the mucosa of the affected gastrointestinal organ should be analyzed on immunostaining or electron microscopy for MRC complexes.     

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。     

Identification of a novel compound heterozygote SCO2 mutation in cytochrome c oxidase deficient fatal infantile cardioencephalomyopathy

Fatal infantile cardioencephalomyopathy (OMIM No. 604377) is a disorder of the mitochondrial respiratory chain and is characterised by neonatal progressive muscular hypotonia and cardiomyopathy because of severe Cytochrome c oxidase deficiency. Here we report a novel mutation in the Cytochrome c oxidase assembly gene SCO2 in an infant with fatal infantile cardioencephalomyopathy despite normal initial metabolic screening. CONCLUSION: In newborns with unexplained muscular hypotonia and cardiomyopathy genetic testing of mitochondrial respiratory chain disorders might be helpful to establish a final diagnosis and guide treatment decisions.     

极长链酰基辅酶A脱氢酶缺乏症研究进展

极长链酰基辅酶A脱氢酶缺乏症是一种较罕见的脂肪酸代谢障碍疾病,根据起病年龄和临床表现分为三型：心肌病型、肝型、肌病型。心肌病型病情重,病死率高。临床诊断可通过血串联质谱(MS/MS)检测血肉豆蔻烯酰基肉碱(C14:1)水平进行,进一步确诊可通过基因诊断、酶学分析及脂肪酸氧化流量分析。治疗上主要包括避免空腹,减少长链脂肪酸的摄入,补充中链甘油三酯等。     

Risk of hepatocellular carcinoma in liver mitochondrial respiratory chain disorders

Mitochondrial respiratory chain disorders (MRCD) are a large group of disorders that can affect any organ besides muscles or the central nervous system. We report two children who presented with neonatal cholestasis and progressive cirrhosis, who subsequently developed hepatocellular carcinoma (HCC). This suggests a particular risk of degeneration in these patients and the importance of a regular screening for secondary liver cancer. Suggestion of HCC should lead to early liver transplantation, which was successful without tumor recurrence in the two patients.     

Foamy myocardial transformation in a child with a disturbed respiratory chain

A female infant presented with signs of general muscle hypotonia and increasing hypertrophy of the heart muscle. There was a constant lactic acidosis worsened after glucose intake. Serum lactate levels were increased up to 6.7 mmol/l. Serum alanine levels reached maximum concentrations of 2800 μmol/l. The patient died after sudden cardiac arrest at 22 months of age. Histology of the heart showed the pattern of foamy myocardial transformation with accumulation of mitochondria and an increased glycogen content. Biochemical analysis of the skeletal muscle and the heart demonstrated signs of a disturbed respiratory chain. The content of cytochromeaa3 protein was decreased in skeletal muscle and heart mitochondria. It is suggested that respiratory chain defects may be the cause of foamy myocardial transformation of the heart.     

Retrospective diagnosis of medium chain acyl-CoA dehydrogenase deficiency

Abstract A male infant is reported who died suddenly and who at post-mortem had pathological evidence suggestive of a genetic defect of fatty acid β-oxidation. A specific diagnosis could not be made enzymatically because of unavailability of suitable tissue for assay. The diagnosis of medium chain acyl-CoA dehydrogenase (MCAD) deficiency was made by specific mutation analysis using the polymerase chain reaction and DNA extracted from the newborn screening card of this infant. This powerful new molecular diagnostic technique should prove to be of use in similar circumstances.