国人connex in 26基因突变与先天性感音神经性耳聋的相关性研究

Study of a mutation in connexin 26 gene associated with congenital sensorineural deafness

目的 :探讨国人耳聋人群中 connexin2 6基因的突变频率和位点。方法 :收集 15例有遗传性耳聋家族史的病例和 2 5 2例散发性先天性耳聋病例血液样本 ,使用 PCR- SSCP方法分析 connexin2 6基因编码区突变。同时采用 PSDM和 Bsi YI酶切的方法 ,直接检测异常 connexin 2 6基因 35 del G的突变。结果 :检出突变样本 4 6例 ,其中散发耳聋患者中 38例 ,突变率为 15 .1% ;有家族史的聋儿 15例中 8例 ,突变率为 5 3.3%。 4 6例中 5份有相似的异常电泳带 ,PCR产物直接测序 ,其形式为 79位 G→ A的突变 ;另外在散发耳聋患者中还发现 2例 2 5 1del T和 2 33del C,PDSM分析未发现有 35 del G的突变。结论 :国人先天性耳聋患者中存在着 connexin2 6基因的高突变率 ,但突变热点与国外报道的不同 ,推测 connexin2

Objective:So far, at least 39 deafness gene loci have been mapped in human chromosome including the connexin 26 gene coding for a gap junction protein. This gene is thought to be linked to hereditary non syndromic sensorineural hearing loss. About 80% of cases of DFNB1 hereditary deafness carry a 30 mer G mutation of connexin 26.Method:To investigate this relationship, we obtained DNA samples from 15 cases with autosomal recessive and autosomal dominant forms of non syndromic deafness. In addition, DNA samples were obtained from 252 unrelated subjects with sporadic hearing loss; parents of these subjects were symptom free. We analyzed the coding region for the connexin 26 gene for mutation using PCR SSCP and sequence analysis and PCR mediated site directed mutagensis.Result:We detected 46 mutations with SSCP. The PCR products that of 5 cases mutations had similar abnormalities in their electrophoresis bands were sequenced. Results from 2 cases of families with hereditary hearing loss and 3 cases of sporadic hearing loss had a G to A transversion at nucleotide 79. In addition, 2cases sporadic hearing loss with 251 delT and 233 delC were found, 35 delG was not detected in 46 cases abnormal PCR products using PSDM assay.Conclusion:High mutation rates were found in China deafness population of connexin 26 gene, but the mutation loci is different from those previously reported. Finding hot spot of connexin 26 gene mutation in China population is important for deafness etiologic diagnosis and affect genetic counseling.