一个非综合征性耳聋家系的GJB2基因突变分析及产前诊断

Mutation analysis of GJB2 gene and prenatal diagnosis in a non-syndromic deafness family

目的确定一个非综合征性耳聋家系的致病基因并为耳聋家庭提供准确的遗传咨询和早期干预,防止耳聋患儿出生。方法应用聚合酶链反应-直接测序方法,对该家系成员缝隙连接蛋白2(GJB2)基因的所有外显子及其与内含子交界处进行测序,寻找基因突变点。对妊娠20周母亲进行产前诊断,行羊膜穿刺,抽取胎儿羊水细胞,提取DNA测定胎儿基因型,预测胎儿听力状态。结果该家系先证者GJB2基因携带235delC、176-191del16bp复合杂合突变,其父亲携带176-191del16bp杂合突变,其母亲携带235delC杂合突变。胎儿携带来自母亲的235delC杂合突变。结论GJB2基因的235delC、176-191del16bp复合杂合突变是导致先证者耳聋发生的原因。胎儿为235delC杂合突变携带者。耳聋患者的基因诊断结合产前诊断对预防耳聋家庭再次生育聋儿可起到明确的指导作用。

Objective To identify the pathogenic gene in a non-syndromic deafness family, provide an accurate genetic consultation and early intervention for deaf family to reduce the incidence of congenital deafness. Methods Mutation analysis was carried out by polymerase chain reaction followed by DNA sequencing of coding region of GJB2 gene. The fetal DNA was extracted from the amniotic fluid cells by amniocentesis at 20 weeks during pregnancy. The genotype of the fetus was characterized for predicting the status of hearing. Results Complex heterozygous mutations 235delC and 176-191del16bp were detected in the proband of the family, heterozygous mutation 176-191del16bp was detected in the father, and 235delC was detected in the mother. Fetus carried 235delC heterozygous mutation inherited from his mother. Conclusions The proband＇s hearing loss is resulted from the complex heterozygous mutations 235delC and 176-191del16bp in GJB2 gene. Fetus is a heterozygous mutation 235delC carrier. Prenatal diagnosis for deafness assisted by genetic test can provide efficient guidance about offspring＇s hearing condition, and prevent another deaf-mute member from birth.