Bayazit Yildirim A, Cable Benjamin B, Cataloluk Osman, Kara Cengiz, Chamberlin Parker, Smith Richard J H, Kanlikama Muzaffer, Ozer Enver, Cakmak Ecir Ali, Mumbuc Semih, Arslan Ahmet
Department of Otolaryngology, Faculty of Medicine, University of Gaziantep, Turkey.
Int J Pediatr Otorhinolaryngol. 2003 Dec;67(12):1331-5. doi: 10.1016/j.ijporl.2003.08.003.
Mutations in Connexin 26 (Cx26) play an important role in autosomal non-syndromic hereditary hearing loss. In this study, our objective was to find out the significance of Cx26 mutations in Turkish families who had hereditary deafness. Fourteen families who had at least two prelingually deaf children per family were included in the study. One affected child from each of the 14 families was selected for single-stranded conformational polymorphism SSCP analysis. Three PCR reactions were used for each subject to amplify the entire Cx26 coding region with overlap. PCR products were sequenced on an Applied Biosystems (ABI) model 3700 automated sequencer. Six of the 14 representative family members (42.9%) demonstrated shifts on SSCP and were subsequently sequenced for Exons 1 and 2 of GJB2 and were tested for the 432 kb upstream deletion. No mutations were found in Exon 1 and no 432 kb deletions were noted. Three different GJB2 mutations were found in Exon 2 of the probands, which were 35delG, 299-300delAT, and 487G > A (M163V). GJB2 mutations were detected in 21.4% of the families. Two patients were homozygous for 35delG and 299-300delAT mutations, and were given a diagnosis of DFNB1 deafness (14.3%). Two different polymorphisms, 457G > A (V153I) and 380G > AG (R127H) were also found. In conclusion, although GJB2 mutations were detected in 21.4% of the families tested, only 14.3% of subject representatives were homozygous and therefore deafness caused by Cx26 mutation segregated with DFNB1. Thus, contribution of GJB2 mutations appears less significant in familial deafness. This necessitates further assessment for the other known gene regions as well as a search for new genetic factors in familial type of genetic deafness.
连接蛋白26（Cx26）突变在常染色体非综合征性遗传性听力损失中起重要作用。在本研究中，我们的目的是找出Cx26突变在患有遗传性耳聋的土耳其家庭中的意义。研究纳入了14个家庭，每个家庭至少有两名语前聋儿童。从这14个家庭中各选取一名受影响儿童进行单链构象多态性（SSCP）分析。对每个受试者进行三次聚合酶链反应（PCR），以重叠扩增整个Cx26编码区。PCR产物在应用生物系统公司（ABI）的3700型自动测序仪上进行测序。14名代表性家庭成员中的6名（42.9%）在SSCP上出现条带迁移，随后对GJB2基因的第1和第2外显子进行测序，并检测432 kb上游缺失。在第1外显子中未发现突变，也未检测到432 kb缺失。在先证者的第2外显子中发现了三种不同的GJB2突变，分别为35delG、299 - 300delAT和487G > A（M163V）。在21.4%的家庭中检测到GJB2突变。两名患者为35delG和299 - 300delAT突变的纯合子，被诊断为DFNB1型耳聋（14.3%）。还发现了两种不同的多态性，即457G > A（V153I）和380G > AG（R127H）。总之，虽然在所检测的家庭中有21.4%检测到GJB2突变，但只有14.3%的受试者代表为纯合子，因此由Cx26突变引起的耳聋与DFNB1相关。因此，GJB2突变在家族性耳聋中的作用似乎不太显著。这需要对其他已知基因区域进行进一步评估，并在家族性遗传性耳聋中寻找新的遗传因素。
