Feng J R, Zhang Y N, Wu X, Yang X J, Chen S T, Ma G C, Luo S G, Zhang Y
Department of Infertility and Sexual Medicine, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou 510630, China.
Zhonghua Yi Xue Za Zhi. 2018 May 15;98(18):1414-1418. doi: 10.3760/cma.j.issn.0376-2491.2018.18.009.
To study the cystic fibrosis transmembrane regulator(CFTR) genotypes and genetic characteristics of a Chinese family with Congenital bilateral absence of vas deferens(CBAVD). Two 33/29-years-old brothers presented with CBAVD-caused obstructive azoospermia were diagnosed on the basis of scrotal palpation, analysis of semen and ultrasound tests. We extracted their genomic DNA as well as their healthy parents' from the peripheral blood leukocytes. To identify CFTR mutations, each of the 27 exons of the CFTR gene and their flanking splice sites sequences were amplified by polymerase chain reaction(PCR) and subsequently studied with Sanger sequencing. Mutations/variations were identified and compared with the control sequence searched in the NCBI database. Homozygous 5T mutation at the splicing site ahead of exon 10 of the CFTR gene was identified in both brothers in association with 13TG and 12TG alleles(13TG-5T/12TG-5T), one of those was inherited from the mother(13TG-5T/11TG-7T), the other was from the father(12TG-5T/12TG-7T). All of the results above had been excluded the presence of other mutations. Genetic study of this family supports that homozygous 5T mutation is associated with CBAVD. Individuals with homozygous 5T alleles are 20 times more possible to transmit this deleterious variant to the next generation than general population. This family we analysed agrees with the previous conclusion that 5T allele is a deleterious and heritable mutation which could cause CBAVD. Considering better genetic counseling, CFTR gene detection and Preimplantation genetic diagnosis(PGD) are suggested for CBAVD couples who seek for reproductive assistance.
研究一个先天性双侧输精管缺如（CBAVD）中国家系的囊性纤维化跨膜传导调节因子（CFTR）基因型及遗传特征。两名33/29岁因CBAVD导致梗阻性无精子症的兄弟，经阴囊触诊、精液分析及超声检查确诊。我们从外周血白细胞中提取了他们及其健康父母的基因组DNA。为鉴定CFTR突变，通过聚合酶链反应（PCR）扩增CFTR基因的27个外显子及其侧翼剪接位点序列，随后用桑格测序法进行研究。鉴定出突变/变异，并与在NCBI数据库中搜索的对照序列进行比较。在两兄弟中均鉴定出CFTR基因第10外显子前剪接位点的纯合5T突变，与13TG和12TG等位基因相关（13TG - 5T/12TG - 5T），其中一个从母亲遗传而来（13TG - 5T/11TG - 7T），另一个从父亲遗传而来（12TG - 5T/12TG - 7T）。上述所有结果均排除了其他突变的存在。该家系的遗传学研究支持纯合5T突变与CBAVD相关。具有纯合5T等位基因的个体将这种有害变异传递给下一代的可能性比普通人群高20倍。我们分析的这个家系与先前的结论一致，即5T等位基因是一种可导致CBAVD的有害且可遗传的突变。考虑到更好的遗传咨询，建议对寻求生殖辅助的CBAVD夫妇进行CFTR基因检测和植入前基因诊断（PGD）。
