非综合征型遗传性聋家系系谱分析及mtDNA 12SrRNA tRNALeu(UUR)tRNASer(UCN) 基因突变分析

目的探讨非综合征型遗传性聋(NSHL)家系中线粒体基因(mtDNA)突变所占比重以及母系遗传的统计学规律.探讨mtDNA突变与遗传性聋的关系及突变在这类家系及散发感音神经性聋(SNHL)中的发生率.方法收集遗传性NSHL家系29个,行家系调查;对家系进行形式遗传学分析、分离分析;采取外周血,从白细胞中抽取DNA;以多重聚合酶链反应(PCR)法检测mtDNA(nt)1 555G、7 445G、3 243G点突变;行mtDNA12SrRNA,tRNALeu(UUR)及tRNASer(UCN)基因序列测定.结果多重PCR检测示mtDNA突变家系12个;形式遗传学分析确定为显性遗传不规则外显的家系,mtDNA突变率高;分离分析结合mtDNA突变检测示母系遗传不具有常染色体遗传基因分离比.经测序证实,12个家系具有mtDNA突变;形式为1 555G突变家系10个,7 445G突变家系2个,未发现3 243G突变家系.结论母系遗传与常染色体显性及隐性遗传基因传递分离比有差异;mtDNA突变在NSHL中占较高比例,主要形式是1 555G及7 445G突变.在散发病例中发生率很低;7 445G结合1 555G点突变筛查对SNHL的诊断有重要意义.多重PCR法是mtDNA多基因突变位点简便的检测方法.

Pedigree analysis and sequence analysis of mtDNA 12SrRNA, tRNALeu(UUR), tRNASer(UCN) gene in nonsyndromic inherited deafness pedigrees

OBJECTIVE: To investigate the proportion of mtDNA mutation in the non-syndromic genetic hearing loss (NSHL) pedigrees and the genetics statistical formulae for maternal inheritance, to study the relationship of mtDNA mutation and inherited deafness, to identify the incidence of the mtDNA mutation in such pedigrees and sporadic patients with Sensorineural hearing loss (SNHL). METHOD: Twenty-nine pedigrees with NSHL were collected. Pedigree Investigation was taken. Modal Genetics Analysis. Segregation Analysis were taken. Blood samples were obtained from these pedigrees. DNA was extracted from the isolated leukocytes. The mtDNA 1555G, 7445G, 3243G mutation were examined by multiplex PCR. The sequence of 12SrRNA, tRNA(Leu(UUR)) and tRNA(Ser(UCN)) gene were examined. RESULT: There are 12 pedigrees with mtDNA mutation (i.e. 10 with 1555G and 2 with 7445G) examing by multiplex PCR. Modal Genetics Analysis showed that in irregular dominate genetic pedigrees, the incidence of mtDNA mutation is higher than that of regular dominate pedigrees. Segregation Analysis with Screening for mtDNA mutation showed that maternal inherited pedigrees did not have the segregate ratio that the autosomal inheritance had. Sequence analysis confirmed that the 12 pedigrees carried mtDNA mutation, among them 10 pedigrees with 1555G mutation, 2 pedigrees with 7445G mutation, no pedigrees with 3243G. CONCLUSION: Maternal inherited pedigrees do not have the segregate ratio of the autosomal inheritance, mtDNA mutation have high incidence in NSHL, mostly are 1555G and 7445G mutation. Screening for mtDNA 7445G mutation combined with 1555G examination is of value to clinical use. Multiplex PCR can diagnose mtDNA multi-mutation quickly and facilely.