7个非综合征型耳聋家系患者的mtDNA A1555G突变分析

目的探讨非综合征型耳聋家系患者mtDNA A1555G突变及其临床特征。方法应用聚合酶链反应、限制性核酸内切酶酶切和DNA测序技术对7个非综合征型耳聋家系112个成员的mtDNA A1555G突变进行检测，并分析听力临床资料。结果7个家系中所有受检的母系成员mtDNA A1555G突变均为阳性，突变性质含同质性和异质性二种；非母系成员及配偶该突变为阴性。突变的性质与临床表型的有关。结论mtDNA A1555G突变可导致非综合征型耳聋和氨基糖苷类抗生素致聋，其突变性质含均质性和异质性两种，且与临床表型相关。     

线粒体DNA A1555G突变的异质性研究进展

线粒体DNA 12S rRNA基因A1555G突变是最早发现的、最常见的与非综合征性耳聋相关的人类线粒体DNA突变。线粒体DNA A1555G突变大多以均质性突变的形式出现,但近来有报道指在不同的家系中也存在异质性的突变形式,且突变负荷与耳聋程度相关。鉴于线粒体DNA A1555G的临床表型在不同个体间存在显著差异,该突变异质性的存在为解释其表型多样性提供了依据。     

120例非综合征性耳聋患者线粒体A1555G和Cl494T突变分析

目的分析温州地区120例耳聋患者的致聋原因,并探讨线粒体ONA（mitochondrial DNA,mtDNA）12S rRNA基因A1555G和C1494T突变与耳聋之间的关系。方法对我院收集的120例耳聋患者进行分子流行病学的调查,并针对线粒体1555和1494位点进行引物设计,通过PCR扩增,产物Sanger测序后比对标准序列,检测A1555G和C1494T突变的频率以及和患者使用氨基糖苷类抗生素的相关性。结果在120例重度耳聋患者中具有氨基糖苷类抗生素用药史的有66例（55％）,家族性遗传耳聋有22例（18．3％）,近亲结婚可能致聋有10例（8．3％）,不明原因的耳聋有22例（18．3％）;我们还发现,有9例患者携带线粒体A1555G突变,突变的阳性率为7．5％,1例携带C1494T突变,阳性率为0．83％,这10例患者均有用药史。结论遗传因素和氨基糖苷类用药史是导致耳聋的重要原因,其中Al555G突变和C1494T突变是耳聋较为常见的线粒体DNA突变,这对早期诊断和预防药物性耳聋具有一定的临床意义。     

中国人非综合征性耳聋患者线粒体基因组C1494T突变筛查

目的进行非综合征性聋患者的线粒体DNA C1494T突变的分子流行病学调查。方法对中国人群中20例氨基糖甙类药物致聋患者、136例散发的非综合征性聋患者以及50例非综合征性聋家系先证者，以聚合酶链反应结合限制性片段长度多态性分析法检测线粒体DNA C1494T突变的发生情况。结果全部受检者无线粒体DNA C1494T突变的发生。结论中国人群中非综合征性聋患者的线粒体DNA C1494T突变的发生率较低，且明显低于线粒体DNA A1555G的突变发生率。通过聋病分子流行病学调查，提示线粒体DNA C1494T突变不是氨基糖甙类药物致聋的主要病因。     

近亲结婚所致非综合征型耳聋家系的线粒体基因突变分析

目的对一个呈母系遗传的非综合征型耳聋大家系进行线粒体DNA的突变检测。方法收集湖南省一个非综合征型遗传性耳聋家系成员外周静脉血，提取基因组DNA（含线粒体DNA），设计特异性引物对目的片段进行PCR扩增，直接测序检测突变类型。结果测序结果显示，线粒体12S rRNA基因A1555G突变为该家系的致病突变，非母系成员不存在这一突变。结论该家系中部分成员使用氨基糖甙类抗生素后出现耳聋，可能是因为药物与线粒体12S rRNA基因的A1555G突变共同参与了听力损伤过程。     

线粒体DNA A1555G突变在新生儿大规模筛查的临床意义

目的 探讨在新生儿中进行线粒体DNA(mitochondria DNA,mtDNA)A1555G突变基因大规模筛查在预防药物性耳聋的必要性.方法 随机取2008年在深圳市出生的1000名新生儿的血滤纸标本,用Chelex-100树脂提取DNA,PCR扩增,变性高效液相色谱法(denaturing hig-performance liquid chromatography,DHPLC)进行mtDNA A1555G突变基因筛查,计算出阳性突变频率.结果 1000名新生儿血滤纸样本中,共检测出2例样本存在mtDNA A1555G突变,突变率为0.2%.结论 mtDNA A1555G突变在新生儿中出现的频率较高,对其进行mtDNA A1555G突变大规模筛查发现氨基甙类抗生素敏感个体,能有效地对新生儿及其家族高危人群进行合理性指导用药,从而更好地预防药物性耳聋.     

氨基糖甙类抗生素致聋患者线粒体DNA 1555G点突变分析

目的考察１５５５Ｇ点突变在氨基糖甙类抗生素致聋家系及散发病例中的发生率,为建立相应的基因诊断方法提供依据。方法收集有明确氨基糖甙类抗生素应用史的两个母系遗传耳聋家系和７个散发病例,以及部分亲属２６人的外周静脉血标本,从白细胞中提取ＤＮＡ,多聚酶链反应扩增线粒体ＤＮＡ目的片段,Ａｌｗ２６Ⅰ限制性内切酶检测１５５５Ｇ点突变。结果两个家系的１４份样品为１５５５Ｇ点突变阳性,散发病例及部分亲属的１２份样品全部为１５５５Ｇ点突变阴性。结论１５５５Ｇ点突变在氨基糖甙类抗生素致聋家系中的发生率较高,在散发病例中的发生率低。１５５５Ｇ点突变筛查有潜在的临床应用价值。     

线粒体DNA A1555G和961 insC双重突变导致的非综合征型遗传性耳聋

目的探讨一个非综合征型遗传性耳聋大家系线粒体DNA(mitoehondrial DNA，mtDNA)突变类型。方法临床听力测试已明确诊断，并收集非综合征型遗传性耳聋分支家系中33人及6例散发聋患者的外周静脉血样本，从白细胞中提取DNA，聚合酶链反应扩增mtDNA目的片段，分别用BsmA I、Apa I及Xba I限制性内切酶检测1555G、3243G和7445G点突变，对相关的扩增片段进行基因测序。结果酶切检测，家系中17例耳聋患者均为1555G点突变阳性，非母系成员及散发聋病例均为阴性。测序结果：6例酶切显示1555G突变阳性病例均发现(nt)1555A→G转换和(nt)961C插入，3243G、7445G点突变阴性。结论在该非综合征型遗传性耳聋大家系中，mtDNA 12SrRNA基因区域A1555G和961insC的双重突变可能共同参与了听力损害的过程。     

七个非综合征型耳聋家系患者的mtDNA A1555G突变性质与特点

目的 探讨非综合征型耳聋家系患者mtDNA A1555G突变性质及其特点,探索临床表型多样性的分子遗传学基础.方法 应用聚合酶链反应-限制性片段长度多态和实时荧光-扩增阻碍突变系统-定量PCR(real time-amplification refractory mutation system-quantitative PCR,RT-ARMS-qPCR)检测7个非综合征型耳聋家系71个成员的mtDNA A1555G突变,并收集、分析其临床资料.结果 7个家系中所有受检的母系成员mtDNA A1555G突变均为阳性,突变性质含同质性和异质性两种;非母系成员及配偶该突变为阴性.7个家系mtDNA A1555G同质性突变的拷贝数与耳聋轻重程度相关(R=0.341,P=0.022);mtDNA A1555G异质性突变的拷贝数与耳聋轻重程度相关(R=0.85,P=0.015).结论 mtDNA A1555G突变可导致非综合征型耳聋和氨基糖甙类抗生素致聋,其突变性质含同质性和异质性两种,且含mtDNA A1555G位点的突变型与野生型的比例与耳聋的严重程度密切相关.     

母亲与子代间线粒体基因组A3243G突变率的关系

目的 研究母亲和子代之间A3243G突变率的关系.方法 收集50个携带线粒体基因组DNA A3243G突变家系进行A3243G突变率分析,以统计学方法研究母亲和子代A3243G突变率的关系.结果 (1)母亲血液与子代血液中A3243G突变率有相关,Pearson相关系数r=0.438,P<0.01;(2)母亲血液与子代...     

Factors that affect hearing level in individuals with the mitochondrial 1555A>G mutation

The mitochondrial 1555A>G mutation is one of the most common mutations responsible for hearing loss in Asians. Although the association with aminoglycoside exposure is well known, there is great variation in the severity of hearing loss. We analyzed hearing levels in 221 Japanese individuals with this mutation and attempted to identify relevant covariants including (i) age, (ii) aminoglycoside exposure, (iii) heteroplasmy ratio, and (iv) other gene mutations. At every age, average hearing levels were worse than those in normal subjects, suggesting that mitochondrial function itself may affect the severity of hearing loss. Although the hearing loss in individuals with the 1555A>G mutation progressed with age, the rate did not differ from that of the normal subjects. Those who had reported aminoglycoside exposure had moderate-to-severe hearing impairment regardless of age, confirming that such exposure is the most important environmental variable. We also confirmed the presence of heteroplasmy, which is known to modify the expression of other mitochondrial diseases, but found no evidence for a significant correlation with hearing impairment. A high prevalence of GJB2 heterozygous mutations was noted, indicating that these mutations may exhibit epistatic interaction with the 1555A>G mutation.     

The 12S rRNA A1555G mutation in the mitochondrial haplogroup D5a is responsible for maternally inherited hypertension and hearing loss in two Chinese pedigrees

We reported here clinical, genetic evaluations and molecular analysis of mitochondrial DNA (mtDNA) in two Han Chinese families carrying the known mitochondrial 12S rRNA A1555G mutation. In contrast with the previous data that hearing loss as a sole phenotype was present in the maternal lineage of other families carrying the A1555G mutation, matrilineal relatives among these two Chinese families exhibited both hearing loss and hypertension. Of 21 matrilineal relatives, 9 subjects exhibited both hearing loss and hypertension, 2 individuals suffered from only hypertension and 1 member had only hearing loss. The average age at onset of hypertension in the affected matrilineal relatives of these families was 60 and 46 years, respectively, whereas those of hearing loss in these two families were 33 and 55 years, respectively. Molecular analysis of their mtDNA identified distinct sets of variants belonging to the Eastern Asian haplogroup D5a. In contrast, the A1555G mutation occurred among other mtDNA haplogroups D, B, R, F, G, Y, M and N, respectively. Our data further support that the A1555G mutation is necessary but by itself insufficient to produce the clinical phenotype. The other modifiers are responsible for the phenotypic variability of matrilineal relatives within and among these families carrying the A1555G mutation. Our investigation provides the first evidence that the 12S rRNA A1555G mutation leads to both of hearing loss and hypertension. Thus, our findings may provide the new insights into the understanding of pathophysiology and valuable information for management and treatment of maternally inherited hearing loss and hypertension.     

The A1555G mtDNA mutation in Danish hearing-impaired patients: frequency and clinical signs

The A1555G mutation of the mtDNA is associated with both aminoglycoside-induced and non-syndromic hearing loss. The A1555G is relatively frequent in the Spanish and some Asian populations, but has only been reported rarely in other populations, possibly because of ascertainment bias. We studied 85 Danish patients with varying degrees of hearing impairment and found two patients with the A1555G mutation (2.4%). Neither had received aminoglycosides. Our study indicates that the mutation might not be uncommon in Danish patients with hearing impairment.     

一个母系遗传非综合征型耳聋家系线粒体12S rRNA G709A位点的突变分析

目的 通过对一个母系遗传非综合征型耳聋家系进行线粒体DNA(mitochondrial DNA,mtDNA)12S rRNA、tRNA~(Ser(UCN))以及核基因GJB2突变分析,研究mtDNA突变与遗传性耳聋的相关性.方法 临床听力测试以明确诊断,收集非综合征型遗传性耳聋家系中18例母系成员和53名对照(包括6名父系亲属、7名配偶对照和40名当地无关对照)外周静脉血样本,采用聚合酶链反应和测序技术对mtDNA 12S rRNA、tRNA~(ser(UCN))和GJB2基因进行突变分析,并对发现的基因突变进行计算机辅助的二级结构模拟分析.结果 测序结果表明,此家系线粒体DNA 12S rRNA存在mtDNA G709A点突变,该突变未见报道;无tRNA~(Ser(UCN))基因突变;对GJB2突变分析发现4例具有299-300 delAT.计算机分析显示12SrRNA的二级结构中第8、9茎环结构发生改变.结论 家系中8例耳聋患者都具有线粒体12S rRNAG709A位点的突变,该突变在正常人群中具有高度保守性,提示GT09A点突变与母系遗传家系成员的进行性耳聋具有相关性;10例具有G709A突变的母系遗传家系成员未出现耳聋的临床表现,提示G709A点突变可能在其他核修饰基因的协同作用下参与了听力损害的过程.     

非综合征型遗传性耳聋两家系线粒体基因突变分析

目的 探讨母系遗传非综合征型耳聋发病机理及7445^G点突变在这类家系及散发感音神经性耳聋病例中的发生率，为建立相应的基因诊断方法提供依据。方法 收集两个母系遗传非综合征型耳聋家系和14个感音神经性耳聋散发病例；抽外周血标本，从白细胞中提取DNA；聚合酶链反应扩增线粒体DNA（mitochondrial DNA,mtDNA）目的片段，分别以Alw 26Ⅰ、ApaⅠ及XbaⅠ限制性内切酶检测1555^G、3243^G及7445^G点突变；行mtDNA 12S r RNA、tRNA^Leu(UUR)、tRNA^Ser(UCN)基因测序。结果 经酶切检测，两家系中12例为7445^G点突变阳性，其余6例及14例散发病例均为阴性，所有病例1555^G、3243^G点突变均阴性；7445^G点突变呈母系遗传。mtDNA测序显示，所有病例1555^G、3243^G点突变均阴性；酶切显示为7445^G突变阳性病例经基因测序均发现有（nt)7445A→G替换。结论 7445^G点突变在母系遗传非综合征型耳聋家系中有较高的发生率，而在散发病例中发生率很低；7445^G结合1555^G点7突变筛查对这类耳聋的诊断有重要意义。