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目的应用母血浆中AIRE基因作为胎儿DNA遗传学标记,探讨无创性产前筛查唐氏综合征(Down syndrome,DS)的可行性。方法提取随机选取的45名正常孕妇血浆中游离DNA,同时以15名非妊娠健康妇女血浆游离DNA作为对照,通过巢式甲基化特异性PCR检测游离DNA中AIRE基因的甲基化状态;提取15名产妇胎盘组织和母血单核细胞中的DNA,检测AIRE基因的甲基化状态;采集20例确诊为DS胎儿的高危孕妇外周血,以45名正常孕妇外周血作为对照,检测AIRE基因甲基化状态。结果正常孕妇血浆中AIRE基因的甲基化率比非妊娠健康妇女高(P<0.01);所有产妇胎盘组织中均能检测到AIRE基因的甲基化,而在母血单核细胞中未检测到;在确诊为DS胎儿的高危孕妇外周血中,AIRE基因的甲基化率远远低于正常胎儿孕妇外周血(P<0.01)。结论 应用巢式甲基化特异性PCR技术检测妊娠期母血浆中AIRE基因的甲基化状态对胎儿DS进行非创伤性产前诊断是可行的。
Objective To evaluate the feasibility of noninvasive prenatal screening for Down syndrome (DS) by using AIRE gene in maternal plasma as a fetal DNA genetic marker. Methods Plasma free DNA was extracted from 45 normal pregnant women randomly selected. The plasma free DNA of 15 non-pregnant women was used as a control to detect the methylation status of AIRE gene in free DNA by nested methylation-specific PCR. 15 maternal placenta tissues and maternal blood mononuclear cells DNA methylation status detection AIRE; 20 cases were diagnosed as high risk fetus of pregnant women with peripheral blood of pregnant women, 45 normal pregnant women as the control of peripheral blood, detect the AIRE gene Methylation status. Results The methylation rate of AIRE gene in plasma of normal pregnant women was higher than that in non-pregnant healthy women (P <0.01). Methylation of AIRE gene was detected in placenta of all the pregnant women but not in maternal blood mononuclear cells The methylation rate of AIRE gene in peripheral blood of pregnant women with high risk of DS fetus was significantly lower than that of normal pregnant women (P <0.01). Conclusion The application of nested methylation-specific PCR to detect the methylation status of AIRE gene in maternal plasma during pregnancy is feasible for noninvasive prenatal diagnosis of fetal DS.