氨基糖甙类抗生素致聋家系线粒体基因突变的分析

Analysis of mtDNA Mutation in Patients with Aminoglycoside Antibiotic-induced Deafness

目的:探讨线粒体DNA(mitochondrialDNA,mtDNA)突变与非综合征性遗传性耳聋的关系,并且建立相应的基因诊断方法。方法:调查并收集2个非综合征性耳聋家系、6个散发病例及25例正常个体的外周静脉血样本,从白细胞中提取DNA,聚合酶链反应扩增mtDNA目的片段,分别用BsmAⅠ、ApaⅠ及XbaⅠ限制性内切酶检测1555G、3243G、7445G和del961Cn点突变,对相关的扩增片段进行基因测序。结果:酶切检测,两家系中全部12例的耳聋患者均为1555G点突变阳性。家系中的其他成员、6例散发病例及25例正常人均为阴性,调查的所有个体(包括患者)3243G、7445G和del961Cn点突变均为阴性。mtDNA测序:酶切显示,1555G突变阳性病例均发现(nt)1555A→G转换,3243G、7445G及del961Cn点突变阴性。结论:1555G点突变呈母系遗传;1555G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,在散发型病例中发生率较低;提示1555G点突变是该类耳聋分子诊断的有用指标。

Objective: To explore the relationship between mtDNA mutation and nonsyndromic inherited sensorineural hearing loss(SNHL), and to establish the methods for the diagnosis of SNHL. Methods: Blood samples from 2 pedigrees, 6 sporadic patients with aminoglycoside antibiotic-induced deafness, and 25 normal subjects were obtained. DNA was extracted from the leukocytes. The mitochondrial DNA target fragments were amplified by polymerase chain reaction(PCR). The 1555G, 3243G and 7445G mutation were defected by BsmAⅠ, ApaⅠand XbaⅠrestriction endonuclease digestion respectively. Some PCR products were analyzed by sequencing. Results: Identified by restriction endonuclease digestion, 12 patients from 2 pedigrees carried 1555G mutation. Others from 2 pedigrees and 6 sporadic patients, 25 mormal objects did not have 1555G mutation. All individuals(including patients) did not have 3243G,7445G and del961Cn mutation. Through DNA sequence analysis, all patients from 2 pedigrees had(nt) 1555A→G transition, and none of them carried 3243G,7445G and 961 mutation. Conclusion: 1555G mutation is maternal inheritance. The 1555G mutation has a high incidence in SNHL, and in sporadic patients is low. It suggests that 1555G mutation might play a role in the molecular diagnosis of SNHL.