Y染色体特异STR位点应用于无创伤性产前胎儿遗传信息的研究

Application of Y-chromosome specific short tandem repeat loci in noninvasive prenatal diagnosis

目的 建立利用孕妇血清进行无创伤性产前胎儿分子遗传信息分析的方法。方法 采集53名11～36孕周的孕妇的血清,利用血清中胎儿DNA,采用”Y-PLEX 6”试剂盒,复合扩增DYS393、DYS19、DYS389 Ⅱ、DYS390、DYS391和DYS385等6个Y-STR位点,PCR产物经基因测序仪电泳检测,用相关软件分析Y-STR基因型。结果 ①29名分娩出生证实为男婴的孕妇,均检测出特异性Y-STR等位基因。检测的6个Y-STR位点,以DYS393位点的检出率最高(29/29);其次是DYS19位点,检出率为62.07％(18/29);再次是DYS390位点,检出率为34.48％(10/29);其余的DYS389 Ⅱ、DYS391和DYS385位点的检出率则较低。②24名分娩出生证实为女婴的孕妇,均未检测出特异性Y-STR等位基因。③根据DYS393位点是否检测出特异性等位基因,以及该基因波峰的高度和波峰面积值,鉴定胎儿性别的准确率达100％。④29名妊娠男婴的孕妇的血清样本,检测出的Y-STR等位基因与“丈夫”的相一致。结论 本研究建立的无创伤性Y-STR分子遗传分析方法,具有多态性丰富、灵敏度高、特异性强等特点,提高了无创伤性产前胎儿性别遗传鉴定的准确性,同时为解决妊娠男婴的亲子鉴定提供了理论依据,具有广泛的应用前景。

Objective To establish a noninvasive method for prenatal genetic analysis by using maternal serum and apply the method in fetal sex determination,paternity testing. Methods Samples of maternal serum from 53 pregnant women (11 to 36 weeks of gestation) were collected. The DNA extracted from each sample was amplified by using'Y-PLEX 6' amplification kit .which enabled the simultaneous analysis of six Y-STR loci including DYS393.DYS19.DYS389 II, DYS390, DYS391 and DYS385. The PCR products were detected by using ABI PrismTM 377 Sequencer and genotyped by related analysis software. Results (1) Y-STR specific alleles were detected in the maternal sera of all 29 mothers bearing male babies. Among the six Y-STR loci,specific alleles were detected in 29/29 at DYS393 locus,in 18/29 at DYS19 locus and in 10/29 at DYS390 locus. (2) Y-STR specific alleles were not detected in maternal sera of 24 pregnant women bearing female babies. (3) According to the presence of specific alleles at DYS393 locus and the value of allelic peak height and peak area, the accuracy of fetal sex determination was 100% . (4)The observed Y-STR alleles of each prenatal specimen from pregnant women with male fetuses were the same as the results of their husbands. Conclusion The assay of highly polymorphic Y-STR genotyping system developed by the authors provided a sensitive, accurate and non-invasive method to prenatal diagnosis. Our results demonstrate that fetal sex can be accurately determined and imply that paternity testing could be performed for pregnant women carrying male fetuses.