76例听神经病患者OTOF基因突变分析

目的对散发听神经病患者进行OTOF基因突变筛查,了解中国听神经病患者中是否存在该基因的热点突变位点。方法选取解放军总医院门诊2003～2005年确诊的散发听神经病患者76例,采集患者外周静脉血,提取基因组DNA;选取OTOF基因已经报道的存在突变或位于突变附近的9个外显子,应用Primer5软件设计9对引物,采取聚合酶链式反应(PCR)扩增,应用PCR产物直接测序法进行OTOF基因突变检测;使用DNAStar软件进行测序序列的对比分析。结果本研究共发现了OTOF基因的8种多态位点。1名温度敏感性听神经病患者检测到82769delAG缺失突变,位于OTOF基因第25外显子上的AG缺失突变导致氨基酸在993位发生改变,翻译截止于1000位氨基酸处,该患者并未检测到OTOF基因的其他突变。56842A/C、82885C/A、92905G/A为已知多态位位点,其中56842A/C和92905G/A多态在NCBI显示的不同人群的多态频率与本研究的多态频率无差异。2例患者发现76378C/T杂合突变(突变率2.63%)、3例患者发现82913G/A杂合突变(突变率3.95%),这两种突变分别位于第15内含子和第25内含子,考虑为本研究发现的新的单核苷酸多态。11例患者发现92995C/T杂合突变(突变率14.47%),5例患者发现96888C/T杂合突变(突变率6.58%),这两种突变分别位于第39外显子和第44外显子,但均没有引起氨基酸的改变。结论本研究在散发听神经病患者中发现了8种OTOF基因多态位点,并未发现国外报道的已知突变,这意味着中国听神经病患者可能存在OTOF基因新的突变,或者存在其它相关致病基因。

Analysis of OTOF Gene Mutations in 76 Cases of Auditory Neuropathy

Objective To perform mutation screening on the OTOF gene of 76 Chinese patients with sporadic auditory neuropathy for investigating whether the patients contained mutational hotspots in the OTOF gene,identifying the distribution and frequencies of OTOF mutations,and detecting new mutation points in the OTOF gene.Methods Genemic DNA samples were extracted from peripheral venous blood samples of the patients.9 primer pairs were designed using the Primer 5.0 software package for 9 exons of the OTOF gene,in which mutations had been discovered in the past.The exons were amplified using polymerase chain reaction(PCR),and direct sequencing of the PCR products was performed to detect OTOF mutations.For analysing the sequence data,the DNAStar 5.0 software package was used.Results 8 types of OTOF polymorphic alleles were discovered in this study.Among them,the 82 769delAG deletion mutation was only found in a patient diagnosed with temperature sensitive auditory neuropathy.In exon 25 of this patient's OTOF gene,the AG deletion mutation caused the replacement of amino acid at positions 993~999 and resulted in a truncated protein at position 1 000 amino acid(exon 26),which caused an early stop codon.(This protein has 1997 amino acids in all).Nevertheless,no other mutations were found in this patient's OTOF gene.The heterozygous 76 378C/T and 82 913G/A polymorphisms were single nucleotide polymorphisms(SNP) discovered in this study.Other SNP found were 56 842A/C,82 885C/A,and 92 905G/A,which had been already published by NCBI.In addition,92 995C/T and 96 888C/T were heterozygous mutations found in the exons,but did not cause the replacement of acid amino.Conclusion Eight SNPs were found in the OTOF gene of the Chinese patients in this study.However,mutations,which were previously identified in other ethnic origins in the literature,were not found in these patients.Thus,the result implied that the Chinese patients with auditory neuropathy may contain new OTOF mutations or other relevant disease-causing genes.