母胎间差异甲基化片段在无创性产前诊断中的应用价值

目的探讨HLCS、RASSF1A片段在母胎间甲基化状态的差异并评估其在无创性产前诊断中的应用价值。方法收集388例孕妇血浆,其中126例同时收集外周血细胞及胎盘（或绒毛）组织,采用甲基化敏感性限制性酶切联合荧光定量PCR（MSRE＋PCR）技术,检测母胎间HLCS基因、RASSF1A基因甲基化状态的差异,分析其影响因素,并根据孕妇血浆中胎源性HLCS/RASSF1A浓度比值判断胎儿21号染色体数目。结果研究证实HLCS及RASSF1A在胎盘或绒毛组织中均呈高甲基化状态,而在母体外周血细胞呈现低甲基化状态,且这种甲基化差异不受孕妇年龄、孕周、胎儿性别的影响。采用MSRE＋PCR技术对孕妇血浆中HLCS、RASSF1A片段的检出率分别为97.4%和96.9%。计算274例正常妊娠孕妇血浆中胎源性HLCS/RASSF1A比值,确定其95%的参考值范围为0.34～2.02,以此为标准判断102例胎儿21号染色体数目,其中98例二倍体妊娠的准确率为95.9%（94/98）,4例21三体综合征妊娠均获正确诊断。结论高甲基化HLCS、RASSF1A基因可作为孕妇血浆中胎源DNA的标志物,且有望根据孕妇血浆中甲基化HLCS/RASSF1A浓度比值进行21三体综合征的无创性产前诊断。

Noninvasive prenatal diagnosis implication of differentially methylated DNA in noninvasive prenatal diagnosis

Objective: To reveal the differential methylation status of HLCS and RASSF1A between fetal and maternal DNA and to clarify their values in noninvasive prenatal diagnosis.Methods: Maternal plasma samples were collected from 388 singleton pregnancies,placental or chorionic villi tissue were also obtained in 126 cases of them.Methylation sensitive restriction enzyme digestion followed by fluorescence quantitative PCR(MSRE + PCR) were employed in analyzing the methylation status of HLCS and RASSF1A.The possible...