21号染色体上胎儿特异性基因SNP位点杂合率测定及意义

摘要

目的 检测中国人群中21号染色体上胎儿特异性基因单核苷酸多态性(SNP)位点的杂合率,为无创诊断唐氏综合征(DS)提供依据.方法 分别检测89例孕妇(孕妇组)分娩前后的基因表达水平,并以100例年龄匹配的健康女性作为对照组,选择胎儿特异性基因；通过多重连接探针扩增技术(MLPA)检测特异性基因mRNA-SNP位点的状态,计算胎儿特异性基因mRNA-SNP位点的杂合率.结果 PLAC4和COL6A2基因表达量在孕妇组分娩前均显著高于分娩后和对照组(P均＜0.05),故确定PLAC4和COL6A2作为研究对象；本研究对象mRNA-SNP杂合率不同于NCBI,尤以rs76461221,rs59066201及rs1044598位点为著.结论 不同人群间SNP杂合率具有极大差异,临床可采用MLPA半定量检测孕妇外周血中胎儿游离RNA无创诊断DS.%Objective To investigate the heterozygote frequencies of single nucleotide polymorphism(SNP) loci from placental mRNA in the Chinese, so to find the fit SNP loci for noninvasive prenatal diagnosis of Downs syndrome. Methods The concentrations of placental expressed genes in 89 healthy pregnant (pregnant group) pre-and post-delivery were detected, and 100 non-pregnant individuals (control group) were chosen as control, then the fetal specificity genes were selected. Then the states of SNP loci of placental mRNA were detected by multiplex ligation-dependent probe amplification ( MLPA)to calculate the heterozygote frequencies. Results The expressed levels of PLAC4 and COL6A2 in pre-delivery pregnant group were significantly higher than those in post-delivery pregnant group and control group (both P < 0.05), so the PLAC4 and COL6A2 were chosen as the interested objects. The SNP loci of placental mRNA was different from NCBI, especially for rs76461221, rsS9066201 and rs 1044598. Conclusion The heterozygote frequencies of SNPs are different in different races of people. This kind of a semiquantitalive MLPA method can be carried out for noninvasive prenatal diagnosis of Downs syndrome in clinic.