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目的通过对常见致聋基因的筛查,初步了解陕西省部分耳聋人群的分子遗传病因及其特点。方法在知情同意的基础上,采集陕西地区283例非综合征型聋哑学生外周静脉血,提取基因组DNA,应用多聚酶链反应(polymerase chain reaction,PCR)扩增GJB2基因编码区、SLC26A4基因第8、第19外显子及线粒体DNA(mi-tochondria DNA,mtDNA)目的片断,Alw26Ι限制性内切酶酶切检测m1555A>G点突变,对酶切阳性标本和GJB2基因编码区及SLC26A4基因的第8、第19外显子进行DNA测序。结果 283例患者中,9例(3.18%,9/283)存在线粒体DNA12SrRNAm.1555A>G均质性突变;55例为GJB2基因突变所致(包括纯合、复合杂合或显性携带者),突变频率为19.43%(55/283),8例为GJB2基因突变携带者。c.235delC和c.299_300delAT等位基因频率分别为14.13%(80/566)和3.89%(22/566),占所有GJB2基因致病等位基因数的87.18%(102/117),是该地区的热点突变;7例为SLC26A4基因的双等位基因突变,突变频率为2.47%(7/283),13例携带SLC26A4基因单等位基因碱基改变,c.919-2A>G和c.2168A>G(p.H723R)占所有SLC26A4基因碱基改变等位基因数的88.89%(24/27)。结论 GJB2基因突变是导致陕西省聋哑学生听力损失的主要原因,c.235delC是其最常见的突变形式,c.919-2A>G和c.2168A>G(p.H723R)为SLC26A4基因主要的两种突变形式。对该地区耳聋患者行三个常见基因筛查,将为25.08%(71/283)患者提供明确分子病因学诊断,并将对32.51%(92/283)的患者及家族成员给予咨询。
Objective To understand the molecular genetic causes and characteristics of some deaf people in Shaanxi Province through screening common deaf genes. Methods Based on the informed consent, 283 non-syndromic deaf students were collected from peripheral venous blood in Shaanxi province for genomic DNA extraction. The coding region of GJB2 gene was amplified by polymerase chain reaction (PCR) , Exon 19 and mi-tochondria DNA (mtDNA) fragments and Alw26I restriction enzyme digestion were used to detect the m1555A> G point mutation. The positive clones of the positive samples and GJB2 gene coding region and SLC26A4 gene 8, exon 19 DNA sequencing. Results Mitochondrial DNA 12SrRNAm.1555A> G homozygous mutations were found in 9 (3.18%, 9/283) of 283 patients. 55 patients were caused by mutations of GJB2 gene (including homozygous, compound heterozygous or dominant carriers) , Mutation frequency was 19.43% (55/283), and 8 cases were carriers of GJB2 gene mutation. The frequencies of c.235delC and c.299_300delAT alleles were 14.13% (80/566) and 3.89% (22/566) respectively, accounting for 87.18% (102/117) of the total number of alleles of all GJB2 genes, 7 cases were bi-allelic mutation of SLC26A4 gene. The frequency of mutation was 2.47% (7/283). The single nucleotide polymorphisms of SLC26A4 gene in 13 cases were changed, c.919-2A> G and c .2168A> G (p.H723R) accounted for 88.89% (24/27) of the total number of alleles of all SLC26A4 gene changes. Conclusions GJB2 gene mutation is the main cause of hearing loss in deaf-mute students in Shaanxi Province. C.235delC is the most common mutation, c.919-2A> G and c.2168A> G (p.H723R) are the major gene of SLC26A4 Two kinds of mutation form. Three common genetic screening tests for deaf patients in the area will provide a clear molecular etiological diagnosis for 25.08% (71/283) of patients and will consult 32.51% (92/283) of patients and their family members.