人工耳蜗植入患者常见聋病相关基因突变与内耳畸形的相关性分析

Deafness-Related Gene Mutations and Inner Ear Malformations Cochlear Implantation Recipients

目的通过对250例接受人工耳蜗植入手术的患者进行常见聋病相关基因突变检测,分析人工耳蜗植入的感音神经性听力损失群体中常见致聋基因的流行情况及突变频率,探讨基因突变与内耳畸形的关系,研究开展遗传咨询和人工耳蜗植入术前评估的科学途径。方法收集在我院接受工耳蜗植入手术的250例患者的临床资料,签订知情同意书后采全血,提取外周血基因组DNA,设计特异性扩增引物后利用多重PCR技术扩增目的片段进行纯化,采用华大基因公司定制的基因片段捕获芯片进行22个聋病相关基因共159个突变位点筛查。总结人工耳蜗植入群体基因突变的分布规律及突变频率,探讨基因突变与内耳畸形的相关性。结果所有250例患者中有77例患者检出基因突变,突变频率为30.80%(77/250)。其中SLC26A4基因突变频率为13.60%(34/250),占所有突变阳性患者的44.16%(34/77),共检出13种序列改变,其中23例患者检出c.919-2A>G突变,占SLC26A4基因突变患者的67.65%(23/34),等位基因频率为5.2%,是该基因突变检出率最高的突变形式。有33例患者检出GJB2基因突变,突变频率为13.20%(33/250),占所有突变阳性患者的42.86%(33/77),共检测到GJB2基因7种致病突变,其中GJB2双等位基因突变23例,突变频率为9.2%(23/250),有20例患者检测到c.235delC突变,有18例患者检测到c.299-300delAT突变,等位基因频率分别为5.4%和3.8%。250例患者中6例检出mtDNA 12SrRNA突变,突变频率为2.4%(6/250)。2例患者检出GJB3基因突变,突变频率为0.8%(2/250)。分析表明大前庭水管综合征(Large ves tibular aqueduct syndrome,LVAS)与内耳结构正常的SLC26A4基因突变携带率存在统计学差异(P<0.001),LVAS伴不完全分隔Ⅱ型(Incomplete partition typeⅡ,IP-Ⅱ)与内耳结构正常的SLC26A4基因突变携带率存在统计学差异(P<0.001),而LVAS与LVAS伴IP-Ⅱ的SLC26A4基因突变结果的差异没有统计学意义(P=0.059)。GJB2基因突变患者合并内耳畸形的比例较低。结论SLC26A4基因突变和GJB2基因突变在遗传性耳聋人群中有较高的发生频率。c.919-2A>G突变和c.235delC突变分别是人工耳蜗植入群体中SLC26A4基因突变和GJB2基因突变的常见形式。SLC26A4基因突变是LVAS发生的主要分子病因。LVAS及LVAS伴IP-Ⅱ与SLC26A4基因突变有明确的相关性,单纯IP-Ⅱ与SLC26A4基因突变可能无关。GJB2基因突变与多数内耳畸形无关。开展常见聋病基因的突变诊断有助于人工耳蜗植入的术前评估。

Objective To report prevalence and mutation frequency of deafness genes in the population of cochlear implantation recipients,investigate the relationship between gene mutations and inner ear malformation,and determine a scientific approach to genetic counseling and pre-operative evaluation of cochlear implantation candidates.Methods Clinical data of 250 patients with cochlear implantation in our hospital were collected.Informed consents were signed prior to the collection of 5 ml peripheral blood.Genomic DNA was extracted,and a gene chip customized by Beijing Genomics Institution was used to detect 159 mutation sites in 22 deafness-associated genes.Result Deafness gene mutations were detected in 77 patients(30.80%).The mutation frequency of SLC26A4 gene was 13.60%(34/250),accounting for 44.16%(34/77)of detected mutations.Thirteen sequence changes were detected,with c.919-2A>G being the most common(n=23,67.65%)with an allele frequency of 5.2%.The mutation frequency of GJB2 gene was 13.20%(33/250),accounting for 42.80%(33/77)of detected mutations.Seven mutations were pathogenic,including biallelic mutations(n=23,mutation frequency=9.2%).Mutations included c.235delC(n=20,allele frequency=5.4%)and c.299-300delAT(n=18,allele frequency=3.8%).mtDNA12Sr RNA mutations were detected in 6 patients(mutation frequency=2.4%).GJB3 gene mutation frequency was 0.8%(2/250).Statistical analysis showed that SLC26A4 gene mutations were correlated with LVAS(P<0.001),but GJB2 gene was not related with inner ear malformation.Conclusion SLC26A4 and GJB2 mutations have higher frequency of occurrence in the hereditary deafness population.The c.919-2A>G and the c.235delC mutations are common forms of SLC26A4 mutation and GJB2 mutation among cochlear implantation recipients.LVAS and LVAS with IP-II are closely related to the SLC26A4 gene,but IP-II without EVA may be unrelated to the SLC26A4 gene.The GJB2 gene mutations are not responsible for most inner ear malformations.Genetic diagnosis of common deafness-related genes contributes to pre-operative evaluation of cochlear implantation.