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目的 分析一个遗传性非综合征型耳聋家系的突变,并探讨缝隙连接蛋白beta 2 (gapjunction protein beta2 ,GJB2 )基因2 35 del C突变是否会加重线粒体A15 5 5 G突变导致的非综合征型耳聋症状。方法 对一个母系遗传性非综合征型耳聋核心家系72个成员取外周血提取DNA,经聚合酶链反应扩增后,利用Alw2 6 限制性内切酶酶切及直接测序验证,对其线粒体DNA突变进行研究;利用Apa 限制性内切酶酶切及直接测序验证,筛查核心家系中GJB2基因2 35 del C突变情况,并对GJB2基因2 35 del C和线粒体A15 5 5 G突变的关系进行研究。结果 在2 7名母系成员中均发现具有线粒体A15 5 5 G突变,呈母系遗传;具有耳聋表型的为2 1人(77.8% ) ,家族外显率高;所筛查的包括配偶在内的72名个体中,仅3例具有GJB2基因2 35 del C杂合子突变,且均出现在母系成员中,但3例的耳聋表型却不同。结论 线粒体A15 5 5 G突变是本家系耳聋遗传易感性的基础,在该家系中GJB2基因的2 35 del C杂合子突变未加重线粒体A15 5 5 G突变导致的非综合征型耳聋。
Objective To analyze the mutations in a hereditary nonsyndromic deafness pedigree and to explore whether the G352B2 mutation in gapjunction protein beta2 (GJB2) might aggravate the nonsyndromic deafness caused by mitochondrial A15 55 G mutation symptom. Methods A total of 72 members of a maternal hereditary nonsyndromic deafness family were extracted from peripheral blood and amplified by polymerase chain reaction (PCR). The mitochondrial DNA was digested with Alw2 6 restriction endonuclease and verified by direct sequencing. Apa restriction enzyme digestion and direct sequencing verification were used to screen the genetic variation of GJB2 gene 2 35 del C in the nuclear pedigree. The relationship between GJB2 gene 2 35 del C and mitochondrial A15 55 G mutation the study. RESULTS: Mitochondrial A15 55 G mutation was found in 27 maternal lineages and was maternally inherited. There were 21 (77.8%) with deafness phenotypes and a high family penetrance rate. The screenings included spouses Of the 72 individuals, only 3 had G35B2 C heterozygous mutations in the GJB2 gene, both of which were present in the maternal family, but three had deafness phenotypes. Conclusion Mitochondrial A15 55 G mutation is the basis of genetic susceptibility to deafness in this family. Non-syndromic deafness caused by mitochondrial A15 55 G mutation was not observed in the heterozygous mutation of G352 in GJB2 gene.