云南地区非综合征性聋患儿GJB2、SLC26A4和线粒体DNA12S rRNA基因突变分析

Analysis of the mutations in GJB2, SLC26A4 and mtDNA 12S rRNA gene in children with non-syndromic hearing loss from Yunnan province

目的研究云南地区非综合征性聋患儿GJ B2、SL C 26A4和线粒体DNA12S r R NA基因的突变情况,了解其遗传特征。方法采集2010年1月~2014年5月我院门诊散发的139例先天性重度和极重度非综合征性感音神经性聋患儿外周血,提取DNA。应用飞行质谱技术对GJB2、SLC26A4和线粒体DNA12S r RNA编码区域中8个突变位点进行检测,包括GJB2(35del G、167d e l T、176-191d e l l 6、2 35 d e l C、29 9-3 0 0 d e l AT),SLC26A4(281C→T、589G→A、IVs7-2A→G、1174A→T、12 2 6 G→A、12 29 C→T、I VSl 5+5 G→A、19 75 G→C、2 0 27 T→A、2162C→T、2168A→G)及线粒体DNA12S r R NA(1494→T、1555A→G)。结果 139例耳聋患者中共检出41例存在致聋突变(29.49%)。GJB2基因突变24例(16.11%),其中235del C纯合突变10例,235del C单杂合突变6例,235del C/299-300del AT复合杂合突变8例;SLC26A4基因突变16例(11.51%),其中IVs7-2A→G纯合突变5例,IVs7-2A→G杂合突变4例,IVSl5+5G→A杂合突变2例,I Vs7-2 A→G/12 2 9 C→T复合杂合突变3例,2 0 2 7 T→A杂合突变2例;线粒体DNA12S r RNA基因同质突变1例(0.72%),位点为1555A→G。结论 GJB2基因突变是导致云南地区非综合征性聋患儿听力损失的主要原因,235del C是其最常见的突变形式,IVs7-2A→G为SLC26A4基因主要的突变形式。对本地区耳聋患者行常见基因的筛查,将为部分患儿和家庭提供分子病因学诊断和相应的遗传学咨询。

OBJECTIVE To study the mutations i n GJ B2, SL C 26A4 a n d mt DNA 12 S r R NA ge n e i n children with non-syndromic hearing loss(NSHL), and to investigate the etiology and mutation regularity of hearing loss f rom Yu n na n provi nce. M ETHODS Per ipheral blood was collected and the DNA templates were extracted from 139 NSHL children who were sporadically identified i n ot olog y cl i n ics i n ou r ho s pit a l. M A LDI-TOF-MS Technology was used to detect the coding region eighteen mutations sites of GJB2, SLC26A4 and mt DNA 12 S r RNA, including GJB2(35del G, 167de1 T, 176-191del16, 235 del C, 299-30 0 del AT), SLC26A4(281C→T, 589 G →A, I Vs7-2A→G, 1174A→T, 1226 G →A, 1229C→T, IVSl5+5G →A,1975 G →C,2027T→A,2162C→T,2168A→G), mt DNA 12 S r RNA(1494→T,1555A→G). RESULTS In the 139 patients, 41 cases(29.49%) of disease-causing mutations were detected. GJB2 gene mutation(n=24, 16.11%)included 235 del C homoz ygous mutation(n=10), 235 del C single heterozygosity mutation(n= 6), 235 del C/299-300 del AT double heteroz ygosit y mutation(n=8). SLC26A4 gene mutation(n=16, 11.51%)included IVs7-2A→G homozygous mut at ion(n=5), I Vs7-2A→ G heteroz ygosit y mut at ion(n=4), IVSl5+5G→A heterozygosity mutation(n=2), IVs7-2A→G/1229C→T double heterozygosity mutation(n=3), and 2027T→A heterozygosity mutation(n=2). mt DNA 12 S r RNA gene mutation was found in one child(0.72%), site 1555A→G. CONCLUSION GJB2 gene mutations are the main cause of non-syndromic hearing loss in Yunnan province. 235 del C is its main mutant form. IVs7-2A→G is the main mutant form of SLC26A4 gene. This genetic epidemiological study demonstrated that some deaf children in Yunnan province can be detected at younger ages by genetic testing of three common hearing loss genes. As a result, patients and family member can acquire more effective genetic counseling.