线粒体基因突变与原发性高血压及左心室肥厚的相关研究

目的:探讨线粒体基因突变在原发性高血压(EH)及左心室肥厚发病机制中作用,为临床诊断和治疗EH提供新的思路。方法:选择2006-01-2007-01之间540例EH患者,分为左心室肥厚组(270例)和非肥厚组(270例),进行线粒体突变位点及频率分析。270例健康体检者设为对照组。结果:肥厚组及非肥厚组患者突变位点和频率未发现显著性差异。与对照组比较,肥厚组及非肥厚组C8414T(P=0.01),A8701G(P=0.0001)均差异有统计学意义。结论:线粒体位点突变与EH左心室肥厚关系不甚密切,但是一些特殊位点的点突变因其对线粒体功能的影响,值得进一步研究。A8701G与C8414T突变可能影响了EH的发生发展进程。     

线粒体DNA突变与原发性高血压相关性的研究进展

原发性高血压（EH）作为心脑血管疾病的主要危险因素,严重危害人类健康。前期研究发现,EH在许多家系中都存在母系遗传特性;因此,线粒体DNA（mtDNA）突变成为了探索EH发病机制的新目标。目前已发现多个与EH相关的mtDNA突变位点,这些突变被证实能够导致线粒体氧化磷酸化缺陷,ATP 合成降低,反应活性氧（ROS）增加和诱导线粒体介导的细胞死亡。据此推断,对线粒体功能障碍的深入研究将有望诠释母系遗传性高血压的分子发病机制,而且EH相关的mtDNA突变将有望成为母系遗传性EH诊断的遗传学标志物。鉴于此,本文将对EH相关的mtDNA突变和功能机制进行全面综述。     

线粒体tRNA~(Thr) T15941C突变位点与原发性高血压的相关性

目的探讨线粒体DNA突变和原发性高血压的相关性。方法本文报道一个具有母系遗传特征的中国汉族原发性高血压家系的临床和分子遗传学特征。使用聚合酶链反应(PCR)扩增母系成员和正常对照的线粒体基因,经过数据比对筛选突变并进行相关分析。结果该家系的高血压发病率较高,此外,母系成员的线粒体基因全序列分析结果显示,存在同质性的tRNA~(Thr) T15941C的突变以及ND1C3497T突变,T15941C突变位于tRNA~(Thr)基因T_ψC环上高度保守的61号碱基,突变破坏了原有的57A-61T的碱基配对,生物信息学软件分析也发现T15941C突变改变了tRNA~(Thr)的二级结构,可能会引起线粒体tRNA代谢障碍。结论线粒体tRNA~(Thr) T15941C和ND1C3497T突变可能是这个原发性高血压家系发病的重要分子基础。该家系表现出的线粒体DNA同质性突变,发病年龄等表型差异,提示核基因、环境因素和线粒体遗传背景等可能对tRNA~(Thr) T15941C突变的表型表达有一定的影响。     

线粒体疾病及其对心血管系统的影响

1963年Nass和Nasa~([1])首次发现线粒体DNA(mitochonddal DNA,mtDNA).1981年Anderson等~([2])完成人类mtDNA测序,提出线粒体母系遗传的概念.1988年Holt等~([3])发现mtDNA缺失可导致线粒体肌病;同年Wallace等~([4])在Leber遗传性视神经病(LHON)患者中发现有mtDNA突变.至此,mtDNA突变及线粒体疾病受到广泛关注.     

环境因素及线粒体基因突变在原发性高血压发病机制中的协同作用

目的:探讨环境因素及线粒体基因突变在原发性高血压(EH)发病机制中的协同作用,为临床诊断和治疗EH提供新的思路.方法:在解放军总医院就诊的990例EH患者接受了详细的病史采集、生化检查及线粒体基因测序分析.结果:多元统计分析显示,EH患者收缩压与线粒体A8343G点突变(β=-22.99±9.00, P=0.01),T8603C点突变(β=26.39±10.39, P=0.01)及性别(β=3.52±1.27,P=0.01)相关;动脉舒张压则与的线粒体基因A8343G点突变(β=-16.31±5.44,P=0.01)、性别(β=-0.34±0.03,P<0.01)、心率(β=0.13±0.03, P=0.01)、家族史(β=1.80±0.78, P=0.02)、入选年龄(β=-0.34±0.03, P<0.01)、发病年龄(β=-0.08±0.03, P=0.01)及空腹血糖(β=-1.96±0.80,P=0.01)相关.结论:线粒体多基因突变与环境因素协同作用影响EH患者的血压.     

风湿性心脏病患者心肌、骨骼肌细胞mtDNA突变的相关性研究

目的探讨风湿性心脏病(风心病)患者心肌细胞与骨骼肌细胞线粒体DNA(mtDNA)突变的相关性.方法随机选取56例风湿性二尖瓣狭窄为主患者(下称实验组,冠心病除外),另选10例意外死亡的成人做为正常对照组.术中切取后乳头肌作为心室肌标本,胸大肌作为骨骼肌标本.定量每例患者心肌及骨骼肌mtDNA4977缺失率,分析其相关性及与心功能的关系.结果实验组心肌mtDNA4977缺失率为1.18%～13.75‰,对照组为0～0.06‰,两者有显著性差异(P＜0.01).随着心功能恶化,实验组心肌mtDNA4977缺失率增加.按NYHA心功能分级,Ⅱ级(B组)、Ⅲ级(C组)、Ⅳ级(D组)心肌mtDNA4977缺失率分别为3.79‰、6.32‰和9.28‰,两两比较,P＜0.05.实验组心肌、骨骼肌mtDNA4977缺失率呈正相关(γ=0.75,P＜0.01).结论风心病患者的心肌mtDNA4977缺失率与其心功能损害程度密切相关;其骨骼肌mtDNA4977缺失率与心肌mtDNA4977缺失率呈正相关.     

线粒体基因A3243G突变阳性糖尿病患者的临床特点分析

目的探讨线粒体基因(mtDNA)A3243G突变阳性糖尿病患者的血糖、血压特征,及其与mtDNA突变负荷间的关系。方法选择福建医科大学附属第一医院2006-2017年初筛的mtDNA A3243G突变阳性的20例糖尿病患者及20例mtDNA A3243G突变阴性的糖尿病患者,通过直接测序进一步确认致病性突变。收集这些糖尿病患者的血糖、血压等临床资料并进行分析总结。对突变阳性患者外周血和(或)尿沉渣组织的DNA进行聚合酶链反应(PCR)-限制性片段长度多态性(RFLP)分析,计算突变负荷(即突变型mtDNA所占的比例)。结果经测序确认为mtDNA A3243G突变阳性的糖尿病患者20例,其中9例为单纯糖尿病,11例合并线粒体脑肌病。mtDNA A3243G突变阳性组的体质量指数(BMI)、糖化血红蛋白低于对照组[(17.81±2.07)比(25.23±4.01)kg/m~2,(7.56±2.18)%比(9.58±2.50)%;均P0.01],血乳酸高于对照组[(3.60±1.97)比(1.72±0.40)mmol/L,P0.05]。单纯糖尿病患者的突变负荷、舒张压、血乳酸水平低于糖尿病合并脑肌病患者[(15.03±6.03)%比(55.84±14.67)%,(69.6±9.7)比(78.0±7.5)mm Hg,(1.94±0.25)比(4.49±1.91)mmol/L,均P0.05],年龄、BMI高于糖尿病合并脑肌病组[(51.2±15.6)比(32.6±10.0)岁,(19.0±2.1)比(16.8±1.5)kg/m~2,均P0.05]。同时对6例患者的尿液和血液进行mtDNA A3243G突变定量检测,发现尿液的突变负荷大于血液中的突变负荷。结论 mtDNA A3243G突变单纯糖尿病患者突变负荷低于糖尿病合并脑肌病/肌病患者。对于BMI20kg/m~2、血乳酸偏高的母系遗传糖尿病患者,很有必要进行mtDNA突变检测,尿沉渣组织更适合可用于mtDNA诊断。     

线粒体DNA ND-1基因点突变与2型糖尿病的关系

2型糖尿病患者中线粒体DNA（mtDNA)3316G→A，3316G→A，3394T→C突变频率分别为3.9%(6/152)和5.3%(8/152)，显著高于正常对照者及冠心病患者，提示mtDNA3316G→A，3394T→G突变与2型糖尿病相关。     

mtDNA Cyt-b、 ATPase6在浸润性乳腺癌中的突变及意义

目的 检测线粒体DNA (mtDNA) Cyt-b、ATPase6在浸润性乳腺癌组织和癌旁组织的突变情况,寻找特异性位点.方法 采用PCR结合基因测序方法,对延边朝鲜族地区浸润性乳腺癌患者(30例)的癌组织及癌旁组织进行mtDNA Cyt-b、ATPase6基因测序,对照人线粒体DNA剑桥修定序列,分析其突变情况.结果 在研究对象的乳腺癌mtDNA中共发现Cyt-b基因区有6个高突变发生率位点,即A15326G、C14766T、G15301A、G15043A、T14783C、C15402T,其中A15326G、C14766T突变率最高;而ATPase6基因区共发现3个高突变发生率位点,即C8673T、A8729G、T8955C,其中C8673T、A8729G突变率最高.结论 mtDNA Cyt-b、mtDNA ATPase6高突变发生位点可为浸润性乳腺癌的诊断及乳腺癌细胞线粒体功能评价提供有价值的参考.     

线粒体电压依赖阴离子通道对携带线粒体DNAA4263G突变的细胞株线粒体钙循环的影响

目的 研究线粒体外膜电压依赖阴离子通道(voltage-dependent anion channel,VDAC)在携带线粒体DNA (mitochondrial DNA, mtDNA) A4263G突变的细胞株线粒体钙循环中的作用. 方法 对该家系的4个母系成员(3个血压异常和1个血压正常者)和3名遗传背景相同的对照者建立了传代淋巴细胞系,利用共聚焦显微镜评价VDAC在携带mtDNA A4263G突变的高血压患者细胞线粒体钙循环中的作用. 结果 与正常对照者淋巴细胞比较,突变细胞株线粒体内钙荧光强度及线粒体膜电势(Δψm)降低,加入苍术苷(线粒体通道蛋白开放剂)后正常者线粒体内钙荧光强度增加,而突变携带者没有明显改变,但两者Δψm均降低,加入环孢素A(CsA)后可以抑制苍术苷作用. 结论 线粒体VDAC功能异常导致mtDNA A4263G突变携带者细胞线粒体对钙通透性增加,Δψm降低,加入苍术苷进一步导致Δψm降低,加入CsA后可以抑制苍术苷作用.     

The heteroplasmic 15059G>A mutation in the mitochondrial cytochrome b gene and essential hypertension in type 2 diabetes

AimThe long-term stress of high blood pressure levels increases the risk of a variety of macro- and microvascular complications of type 2 diabetes (T2D). The etiology of essential hypertension (EH) has been explored in depth, but the pathophysiology is multifactorial, complex, and poorly understood. Recent findings showed a role of inherited mutations in mitochondrial DNA (mtDNA) in maternally inherited forms of hypertension. However, an impact of somatic mtDNA mutations in the development of EH is significantly less investigated. In this study, we examined whether the level of heteroplasmy for the 15059G>A mutation in the mitochondrial cytochrome b gene is associated with EH in T2D.Patients and methodsThe heteroplasmy level in mtDNA isolated from blood of 189 diabetic participants randomly selected from general population (124 of whom had EH) was quantified using a real-time PCR.ResultsThe 15059G>A heteroplasmy exceeding 39% was found to be significantly associated with a higher risk of EH (odds ratio 1.96; P (Fisher) 0.032).ConclusionThere is the first evidence reporting association between the mtDNA 15059G>A mutation heteroplasmy and EH in T2D.     

The complete sequence of mtDNA genes in idiopathic dilated cardiomyopathy shows novel missense and tRNA mutations

BACKGROUND: Previous studies have shown that mitochondrial DNA (mtDNA) mutations are often present in patients with myocardial dysfunction. We sought to assess the prevalence and significance of heart mtDNA sequence changes in patients with idiopathic dilated cardiomyopathy (DCM). METHODS AND RESULTS: DNA sequence of all the transfer ribonucleic acid (tRNA), ribosomal RNA (rRNA), and structural genes in cardiac mtDNA of 28 patients with DCM was determined and compared with a control group that had no evidence of heart disease. An increased number of point mutations were found in DCM cardiac mtDNA when compared with controls. Both novel and previously reported mutations were found in mitochondrial tRNA and structural genes. One of these mutations was heteroplasmic and resulted in changing a highly conserved nucleotide in tRNAArg. Novel, heteroplasmic mtDNA mutations (n = 4) specifying changes in moderate to highly conserved amino acid residues were found in COII, COIII, ND5, and cytb. These novel mtDNA mutations were found only in patients with severe reduction in mitochondrial enzyme activities. CONCLUSIONS: Our results indicate that a high incidence of mtDNA nucleotide sequence changes in both tRNA and structural genes are present in DCM. Five heteroplasmic mutations were detected that both changed evolutionarily conserved residues (which may impair the function of proteins or tRNAs) and were associated with specific enzymatic defects. These mutations could play an important role in the pathogenesis of cardiomyopathy.     

Irritable Bowel Syndrome May Be Associated with Maternal Inheritance and Mitochondrial DNA Control Region Sequence Variants

Background and Aim

Mitochondrial dysfunction has been implicated in various functional disorders that are co-morbid to irritable bowel syndrome (IBS) such as migraine, depression and chronic fatigue syndrome. The aim of the current case–control pilot study was to determine if functional symptoms in IBS show a maternal inheritance bias, and if the degree of this maternal inheritance is related to mitochondrial DNA (mtDNA) polymorphisms.

Methods

Pedigrees were obtained from 308 adult IBS patients, 102 healthy controls, and 36 controls with inflammatory bowel disease (IBD), all from Caucasian heritage, to determine probable maternal inheritance. Two mtDNA polymorphisms (16519T and 3010A), which have previously been implicated in other functional disorders, were assayed in mtDNA haplogroup H IBS subjects and compared to genetic data from 344 published haplogroup H controls.

Results

Probable maternal inheritance was found in 17.5 % IBS, 2 % healthy controls and 0 % IBD controls (p < .0001). No difference was found between IBS and control for 3010A, and a trend was found for 16519T (p = 0.05). IBS with maternal inheritance were significantly more likely to have the 16519T than controls (OR 5.8; 95 % CI 1.5–23.1) or IBS without maternal inheritance (OR 5.2; 95 % CI 1.2–22.6).

Conclusions

This small pilot study shows that a significant minority (1/6) of IBS patients have pedigrees suggestive of maternal inheritance. The mtDNA polymorphism 16519T, which has been previously implicated in other functional disorders, is also associated with IBS patients who display maternal inheritance. These findings suggest that mtDNA-related mitochondrial dysfunction may constitute a sub-group within IBS. Future replication studies in larger samples are needed.     

Maternal transmission of diabetes.

Type 2 diabetes mellitus represents a heterogeneous group of conditions characterized by impaired glucose homeostasis. The disorder runs in families but the mechanism underlying this is unknown. Many, but not all, studies have suggested that mothers are excessively implicated in the transmission of the disorder. A number of possible genetic phenomena could explain this observation, including the exclusively maternal transmission of mitochondrial DNA (mtDNA). It is now apparent that mutations in mtDNA can indeed result in maternally inherited diabetes. Although several mutations have been implicated, the strongest evidence relates to a point substitution at nucleotide position 3243 (A to G) in the mitochondrial tRNA(leu(UUR)) gene. Mitochondrial diabetes is commonly associated with nerve deafness and often presents with progressive non-autoimmune beta-cell failure. Specific treatment with Coenzyme Q10 or L-carnitine may be beneficial. Several rodent models of mitochondrial diabetes have been developed, including one in which mtDNA is specifically depleted in the pancreatic islets. Apart from severe, pathogenic mtDNA mutations, common polymorphisms in mtDNA may contribute to variations of insulin secretory capacity in normal individuals. Mitochondrial diabetes accounts for less than 1% of all diabetes and other mechanisms must underlie the maternal transmission of Type 2 diabetes. Possibilities include the role of maternally controlled environments, imprinted genes and epigenetic phenomena.     

线粒体DNA变异与老年2型糖尿病患者易感性的相关性

目的 研究湖北地区老年2型糖尿病(T2DM)患者中线粒体基因突变的发生率及其相关性.方法 采用PCR-RFLP、基因测序技术,对175例老年T2DM患者和200例糖耐量正常的健康老年对照组进行检测.结果 MIND1 3316(G→A)、MTTL1 3243(A→G)、MIND13394( T→C)、MIND14216(T→C) MIND14164(A→G)和MIND2 5178( T→C)变异率分别为3.26％、2.72％、1.71％、4％、34.9％;对照组检出3316(G→A)突变2例(0.99％)、4164 5例(0.99％)、5718(T→C)变异64例(32.3％),未检出3394、4216的点突变;两组间3394(T→C)变异率差别有统计学意义(P＜0.05);且T2DM组5178A基因型血清TC水平低于5178C基因型(P＜0.05),但TG、LDL-C、HDL-C、apoA、apoB、Lp(a)水平两组无统计学意义.结论 3394( T→C)与老年T2DM患者的易感性有一定关联,5178(T→C)变异与湖北地区老年汉族人T2DM的脂代谢相关.     

Mitochondrial gene defects in patients with NIDDM

Summary Non-insulin-dependent diabetes mellitus (NIDDM) has a strong genetic component and maternal factors have recently been implicated in disease inheritance. The mitochondrial myopathies are a group of diseases which often show maternal inheritance as a result of mtDNA defects; some patients have impaired glucose tolerance. Occasional families with maternally inherited diabetes and deafness associated with a deletion or point mutation of mtDNA have been reported. To assess the importance of mitochondrial gene defects in NIDDM, 150 unrelated diabetic subjects from Wales, UK and 68 unrelated patients with diabetes and at least one affected sibling from England, UK were studied. Southern blot analysis did not show any large mtDNA deletions or duplications. One patient had a mutation in the mitochondrial tRNA^leu(UUR) gene at bp 3243. This mutation is commonly associated with the syndrome of mitochondrial encephalomyopathy, lactic acidosis and stroke like episodes (MELAS). Study of this patient and his siblings showed a distinct form of late-onset diabetes associated with nerve deafness but no clinical features of the MELAS syndrome. No diabetic subject was shown to have the mtDNA mutation at position 8344 (tRNA^lys) which has previously been described in the syndrome of mitochondrial encephalomyopathy and red-ragged fibres (MERRF). The role of other mitochondrial gene defects in diabetes and the pathophysiological basis of glucose intolerance in patients with the MELAS mutation requires further elucidation.Abbreviations mtDNA mitochondrial DNA - tRNA transfer RNA - NIDDM non-insulin-dependent mellitus - bp base pair - PCR polymerase chain reaction     

Mitochondrial DNA mutation at np 3243 in a family with maternally inherited diabetes mellitus

Mitochondrial DNA (mtDNA) gene defects may play a role in the development of maternally inherited diabetes mellitus and deafness (MIDD). A family from Southern Italy who showed maternal transmission of type 2 diabetes mellitus with three individuals affected is described. A 10.4 kb deletion and mutations at nucleotide positions (np) 3243, 7445 and 11778 in the mtDNA of six relatives were sought. The mitochondrial np 3243 mutation of the tRNA Leu (UUR) gene was identified in a boy affected by optic atrophy and mental retardation, as well as in his diabetic mother. No other mutations or deletions were found. Our study points out the variable phenotypic expression of the np 3243 mtDNA mutation. This may suggest the presence of other mitochondrial or nuclear mutations required to modulate the phenotype. A clinical and metabolic follow-up of all family members was necessary to understand the role of the np 3243 mutation, especially in one child affected by optic atrophy and mental retardation. Further studies will be aimed at investigating the prevalence of mutations and deletions of mtDNA in type 2 diabetes mellitus. Received: 20 November 1998 / Accepted in revised form: 20 July 1999     

线粒体DNA3537A→G、4824A→G、5351A→G突变与2型糖尿病的相关性研究

目的研究T2DM患者线粒体ND1基因3537A→G和ND2基因4824A→G、5351A→G突变与T2DM的相关性。方法应用PCR-RFLP技术检测145例T2DM和334例正常对照者（NC）线粒体DNA（mtDNA）3537A→G、4824A→G、5351A→G突变情况。结果NC组mtDNA4824A→G突变率高于T2DM组（P＜0．05）。3537A→G及5351A→G突变率在两组中无统计学差异（P〉0．05）。结论mtDNA4824A→G突变可能为T2DM患病的保护因素。3537A→G及5351A→G突变可能与T2DM不相关。     

Specific correlation between the wobble modification deficiency in mutant tRNAs and the clinical features of a human mitochondrial disease

Mutations in mtDNA are responsible for a variety of mitochondrial diseases, where the mitochondrial tRNA(Leu(UUR)) gene has especially hot spots for pathogenic mutations. Clinical features often depend on the tRNA species and/or positions of the mutations; however, molecular pathogenesis elucidating the relation between the location of the mutations and their leading phenotype are not fully understood. We report here that mitochondrial tRNAs(Leu(UUR)) harboring one of five mutations found in tissues from patients with symptoms of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) (A3243G, G3244A, T3258C, T3271C, and T3291C) lacked the normal taurine-containing modification (5-taurinomethyluridine) at the anticodon wobble position. In contrast, mitochondrial tRNAs(Leu(UUR)) with different mutations found in patients that have mitochondrial diseases but do not show the MELAS symptoms (G3242A, T3250C, C3254T, and A3280G) had the normal 5-taurinomethyluridine modifications. These observations were made by using a modified primer extension technique that can detect the modification deficiency in the extremely limited quantities of mutant tRNAs obtainable from patient tissues. These results strongly suggest deficient wobble modification could be a key molecular factor responsible for the phenotypic features of MELAS, which can explain why the different MELAS-associated mutations result in indistinguishable clinical features.