【作者】 韩明昱；

【导师】 戴朴；

【作者基本信息】 中国人民解放军军医进修学院 ， 耳鼻咽喉—头颈外科， 2011， 博士

【摘要】 耳聋基因诊断的诞生对耳聋的诊断及预防产生了重大影响及革命性进步。以全国性聋病分子流行病学研究数据作为理论基础,即中国相当一部分综合征性和非综合征性耳聋仅由为数不多的几个基因突变(GJB2,SLC26A4,线粒体C1494T和A1555G)所致,耳聋基因诊断在我国实现了“基础→临床”的顺利转化,新的耳聋整体预防思路和方法逐步形成与建立。本课题通过规模化多层次的遗传性耳聋预防与干预研究,包括：对聋人群体婚配前的基因检测与遗传指导；对聋人夫妇的生育前基因检测与后代听力情况的预测；对分子病因和后代患病风险明确的家庭生育/再生育前的基因检测和产前诊断；以及对孕期女性的耳聋基因普遍性筛查预防耳聋出生缺陷；为建立我国遗传性耳聋预防与干预策略提供理论基础和依据,并进一步推动耳聋基因诊断、遗传咨询和耳聋产前诊断工作的广泛开展,从而实现减少耳聋出生缺陷,提高人口素质的目标。第一部分耳聋遗传高风险人群的遗传性耳聋预防与干预研究第一节青年聋人的遗传咨询与婚配指导在我们对青年聋人的调查中,有40%的聋人表示希望配偶同为耳聋者,处于婚恋年龄的青年聋人是潜在的巨大的同证婚配群体。由于同证婚配会导致同基因型耳聋者婚配机率增加,如果没有干预,同基因型耳聋患者间的婚配持续发展会导致遗传性耳聋新生儿数的增加。这种同基因型的结合可以通过对聋人婚配前进行分子病因筛查并提供后续的正确婚配指导有效避免,从而防止耳聋垂直传递。本研究中,我们为293名16-27岁的青年聋人进行了婚配前耳聋基因检测,发现39.9%的青年聋人携带常见耳聋基因突变,其中20.1%的青年聋人携带GJB2突变,12.3%青年聋人携带SLC26A4基因突变,7.5%青年聋人携带线粒体A1555G突变(其中54.5%为女性)。确诊为GJB2/SLC26A4耳聋的患者,在择偶时避免选择致聋基因相同的聋人以及携带者,可有效降低生育聋儿的风险率,同时携带线粒体A1555G突变的女性,其后代通过用药指导,可避免药物性耳聋的发生。第二节聋人夫妇的遗传咨询与生育指导虽然聋人群体中同证婚配即“聋-聋”婚配最为常见,但中国绝大部分聋人夫妇希望生育正常听力后代,因此后代听力状态是聋人夫妇最为关心的问题。本研究中,我们为100对聋人夫妇进行了生育前耳聋基因检测并对后代耳聋风险进行了预测,结果发现58对夫妇(58%)至少一方为遗传性耳聋患者,总共34对夫妇(34%)耳聋存在基因型冲突,其中22对夫妇(22%)为相同耳聋基因突变致聋,后代耳聋风险为100%,8对夫妇(8%)后代耳聋风险为50%,1对夫妇(1%)后代耳聋风险为25%,3对夫妇(3%)的后代会携带线粒体基因突变,出生后需要严格用药指导。通过后续的遗传咨询与产前诊断,成功预防2例耳聋后代出生,指导帮助18对聋人夫妇生育正常听力后代。聋人夫妇生育前进行耳聋基因检测可有效降低聋儿出生率。第三节规模化遗传性耳聋家庭的产前诊断耳聋基因诊断配合产前诊断是保障耳聋家庭生育/再生育的关键技术,我们从2005年起开始进行耳聋产前诊断·临床应用,并建立了严谨规范的诊断流程与策略。本研究中,我们为213个通过耳聋基因诊断明确了分子病因与后代患病风险的遗传性耳聋家庭,成功实施了226例次耳聋产前诊断(11个家庭共行2次产前诊断,1个家庭共行3次产前诊断),有效预防46例聋儿出生,其余已出生的141个后代听力100%正常,将隐性遗传耳聋家庭再生育风险25%-50%降至接近于零。在准确的耳聋基因诊断基础上的产前诊断,可从根本上预防和阻断遗传性耳聋,成为实现预防耳聋出生缺陷目标的重要手段。第二部分孕期女性常见耳聋基因筛查和耳聋出生缺陷干预的前瞻性研究先期耳聋流行病学调查数据初步显示,中国人常见耳聋基因突变的携带率高达6%,依赖聋人的筛查和干预尚不足以从根本上阻断遗传性耳聋在整个人群中的传递和发病。如果年轻夫妇在婚检或生育前进行耳聋基因筛查,可避免双方均为同一耳聋突变基因携带者的夫妇生育聋儿,并可及早地发现药物性耳聋敏感个体,通过早期干预,可有效预防耳聋发生。本研究在3000名孕妇中进行了常见耳聋基因筛查,发现146人携带耳聋基因突变,其中91人携带GJB2突变,49人携带SLC26A4突变,6人携带mtDNAA1555G突变,总携带率为4.9%。进一步分析发现12个家庭的夫妇同为GJB2或SLC26A4突变携带者,生育遗传性耳聋的风险为25%,经过后续的遗传指导和产前诊断,避免了这些家庭生育耳聋后代。随后,我们在3000名孕妇生育后进行随访,没有发现耳聋后代出生。这是我们第一次通过基因诊断在正常生育人群实现耳聋出生缺陷预防,这一策略可实现遗传性耳聋的一级预防。更多还原

【Abstract】 Genetic testing exerted a great influence and brought evolutionary progress on diagnosis and prevention for deafness. Based on the results of the national epidemiological study for deafness that a large proportion of both syndromic and nonsyndromic forms of deafness are caused by a small number of genes, genetic testing has been implemented clinically and the followed is coming up with the new idea of prevention for deafness. This study focused on the thoroughly prevention and intervention for hereditary hearing loss, including genetic testing and counseling for deaf youth before marriage; genetic testing and prediction of offspring’s hearing status for deaf couples; genetic testing and prenatal diagnosis for couples who have a deaf child; carrier screening of common deaf genes in pregnant women, in order to provide evidence and theory for the national strategy of prevention for deafness, promote the application of genetic testing in China and eventually reduce the birth rate of deaf children.Part I:The prevention and intervention for hereditary in population with high deaf recurrence riskChapter I Genetic Counseling and Instruction for Deaf Youth Directed by Genetic TestingIn our survey,40% deaf youth are willing to have a deaf spouse and that means the deaf youth is the potential population with "deaf-deaf" marriage mode.This marriage mode will increase the possibility of marriage between the deaf youth caused by same deaf genes,and the deaf couples caused by same deaf genes will increase the number of newborn babies if without the intervention. To decrease the risk of having the deaf offspring,the deaf youth caused by GJB2 or SLC26A4 mutations need to avoid the deaf spouses or carriers caused by same deaf genes, and this can be realized by means of genetic testing before marriage.In this study,293 deaf youth,age 16-27,received the genetic testing. The carrier rate of GJB2, SLC26A4 and mtDNA A1555G mutation were 20.1%,12.3% and 7.5% retrospectively, and 54.5% mtDNAA1555G mutation carriers were female. Then the genetic information and instruction before marriage were offered to them based on results.ChapterⅡGenetic Counseling and Instruction for Deaf Couples Directed by Genetic TestingThe marriage mode of ’deaf—deaf’ is very common in deaf population. Most of deaf couples are eager to receive effective genetic counseling to avoid having a deaf offspring. By means of genetic testing, we analyzed the molecular pathogenesis of 100 deaf couples (200 individuals altogether).118 individuals (58%) were confirmed to be hereditary deafness caused by GJB2, SLC26A4 or mtDNA mutation. There were high deaf recurrence risk in 34 deaf couples.22 of them confronted recurrence risk as high as 100%, as each couple were caused by same deaf genes(GJB2 or SLC26A4).8 of them were with 50% recurrence risk. The offspring in 3 couples with deaf wives caused by mtDNAA1555G mutation would be the same mutation carriers and the the instruction for them was to strictly avoid the administration of aminoglycoside antibiotics. The following visit showed that 2 deaf offspring were avoided and 18 deaf couples gave the birth to normal hearing babies. ChapterⅢ. Prenatal Diagnosis for hereditary deaf families assisted by genetic testingTo be assisted by genetic testing, prenatal diagnosis was carried out in 213 hereditary deaf families.The recurrent risk was 25% in 209 families, including 204 families with one deaf child and 5 families without children, which all couples were GJB2 or SLC26A4 mutation carriers and deaf children were caused by homozygous or compound GJB2/SLC26A4 mutations; The recurrent risk was 50% in 3 families, which one family was of the father and his child with compound SLC26A4 mutations and the mother with heterozygous SLC26A4 mutation, one family was of the wife with POU3F4 c.647G>A heterozygous mutation and the rest one family was of the husband with compound SLC26A4 mutations and the wife with mtDNA A1555G mutation and heterozygous SLC26A4 mutation simultaneously; The recurrent risk was 100% in one family of the deaf couple both caused by GJB2 mutations, and the deaf wife got pregnant by means of artificial insemination with the sperm from the local Human Sperm Bank.226 times of prenatal testing were applied in all 213 families.46 times of prenatal testing showed that the fetuses carried parental mutations simultaneously or the same mutations with probands, and the parents decided to terminate pregnancy; while 180 times of prenatal testing showed that the fetuses carried only one parental mutation or did not carry any mutation from parents, and the following visit showed that 141 families had given birth to babies who were all revealed to have normal hearing by new born hearing screening. Prenatal diagnosis assisted by genetic testing can provide scientific information about offspring’s hearing condition, and the normative workflow and precise strategy highly guarantee the safe and favorable implementation of prenatal diagnosis. PartⅡ:The Genetic Screening of Common Deaf genes in Pregnant Women and Intervention for deaf birth defectSince the carrier rate of common deaf genes in China is as high as 6%, only depending on the prevention and intervention of hereditary deafness in deaf population is not enough to stop the transmitting of deafness in whole population.Genetic screening for young couples can find out the couples who are the same deaf genes’ carriers and then avoid to have deaf offspring.In addition, mtDNA mutation carriers who are sensitive to aminoglycoside antibiotics and individuals with late on-set hereditary deafness can be found in time by means of genetic screening of deaf genes in pregnant women and newborn babies. Early intervention and rehabilitation can prevent them from being deaf. In this study, we carried out genetic screening of common deaf genes in 3000 pregnant women.146 women (4.9%) were confirm to carry common deaf gene’s mutations.91 women(3.03%) were GJB2 carriers,49(1.63%) were SLC26A4 carriers and 6(0.2%) were mtDNA A1555G carriers. The further analysis showed that 12 couples were the same deaf genes(GJB2/S1C26A4) carriers, which means their offsprings would confront 25% deaf risk. The following genetic instruction and prenatal diagnosis assisted them to avoid deaf offsprings. We also finished the following visit in 3000 women and there was no deaf offspring reported. This is the first time to accomplish the primary prevention for deafness in normal hearing population.更多还原