先天性非综合征型耳聋相关基因检测及热点突变分析

目的应用耳聋基因芯片对先天性非综合征型感音神经性聋患儿及有明确遗传史病例的家族成员进行常见耳聋相关基因检测,分析不同的可能已知相关因素引起的先天性聋患儿基因突变的热点位点,探讨突变基因位点与耳聋病因的相关性,并对热点突变基因的家系遗传规律进行初步分析。方法先天性非综合征型感音神经性聋儿童109例,通过CT检查及问卷调查寻找其可能的发病原因。对所有病例均采集血液样本,提取DNA,并以26例健康儿童作为对照组,应用耳聋基因芯片进行常见耳聋相关基因检测,分析突变位点及突变频率与耳聋病因的相关性。同时,对有明确遗传史的5个家族的相关成员进行相应检测,并绘制家系图,对热点突变基因可能的遗传方式进行初步探讨。结果 109例耳聋儿童的外周血样本中,GJB2和SLC26A4基因突变均有较高的检出率,所有病例均未检测到GJB3基因突变。线粒体均质突变检出3例,均有明确的氨基甙类抗生素用药史;实验组基因突变检出率明显高于对照组(P<0.001),有明确遗传病史组突变检出率明显高于无遗传病史组(P<0.001),有前庭导水管扩大组突变检出率明显高于无前庭导水管扩大组(P<0.001);SLC26A4基因突变主要集中于SLC26A42168A>G和SLC26A4IVS7-2A>G位点,与有无遗传病史和有无前庭导水管扩大均有显著相关性(P<0.01),GJB2基因突变主要集中于GJB2235delC和GJB2299delAT位点,本组病例显示其突变率与有无遗传病史无显著相关性(P>0.05);对4个大前庭导水管综合征家系和1个遗传性耳聋家系的分析显示,5个家系的遗传方式均符合常染色体隐性遗传规律。结论先天性非综合征型耳聋患者耳聋相关基因突变率明显高于正常人群,GJB2、SLC26A4基因突变均有较高检出率。本组病例显示GJB2基因突变与家族遗传史无明显相关性,而SLC26A4基因主要在大前庭导水管综合征患者中被检出,并表现出明显的家族遗传性,其遗传方式符合常染色体隐性遗传规律;线粒体均质突变多集中于12SrRNA1555A>G位点,主要在药物中毒性耳聋患儿中被检出。

Common deafness genes Detection and hot mutation spots analysis in patients with congenital non-syndromic hearing loss

Objective The aim of the study was to determine correlation between genetic mutation hot spots and possible etiologies of deafness among a group of children with congenital non-syndromic hearing loss (NSHL) and their family members,and to determine their hereditary patterns.Methods One hundred and nine children with congenital sensorineural hearing loss were evaluated for possible etiological factors by CT examination and questionnaire survey.Blood samples from all patients and some family members and from 26 healthy children (the control group) were taken after informed consent.DNA samples in the blood were extracted and common deafness genes were tested by using of a deafness gene screening chip.Correlation between mutation hot spots and deafness etiologies were examined.The test included members from 5 families with definite hereditary relations and their family trees were drawn to determine the possible inheritance patterns of hot spot mutations.Results There were high detection rates of GJB2 and SLC26A4 gene mutations in this patient population,with no detection of GJB3 gene mutation.Mitochondria homogeneous mutations were detected in 3 cases with history of use of aminoglycoside antibiotics.Detection rates of gene mutations in patients and their family members were higher than in the normal controls (P<0.001).Detection rates in patients with definite genetic histories and in those with large vestibular aqueduct syndrome (LVAS) were higher than those without genetic history or LVAS (P<0.001).SLC26A4 mutations often involved SLC26A4 2168 A > G and SLC26A4 IVS7-2 A > G,and were significantly related to positive genetic history and LVAS (P<0.01).GJB2 235 del C and GJB2 299 del AT were the most common GJB2 mutations and showed no significant correlation with a genetic history (P>0.05).The analysis of 4 families with LVAS and 1 family with hereditary deafness showed that the mode of inheritance was autosomal recessive.Conclusions Mutation rate of deafness gene is higher in patients with congenital NSHL than in normal population.GJB2 and SLC26A4 mutations are most common in these patients.GJB2 mutations are not correlated to genetic history.SLC26A4 mutations are mainly detected in patients with LVAS with a significant familial autosomal recessive transmissibility.Mitochondria mutations mainly involves 12 S rRNA 1555 A > G detected in patients with drug toxicity history.