利用短串联重复序列无创性产前诊断21-三体综合征

目的:探索短串联重复序列用于无创性产前诊断21号染色体非整倍体异常的可行性。方法:选择进行遗传咨询的孕妇及其配偶共50对,以血红蛋白γ链染色结合显微操作分离获取母血中胎儿有核红细胞,经PEP扩增细胞基因组后,对3个21染色体位点D21S11、D21S1411、D21S1412进行PCR扩增。同时对各对夫妻外周血DNA进行上述基因位点扩增,聚丙烯酰胺凝胶电泳后胎儿及其双亲的基因型对比分析。结果:50例均获取胎儿细胞样本,平均4.55±2.60个/ml。其中3例扩增失败,其余47例D21S11、D21S1411及D21S1412位点的有效信息率分别为85.11%(40/47)、78.72%(37/47)、76.60%(36/47)。3个STR位点联合应用,对45例样本成功鉴定了细胞的胎儿源性并准确判断胎儿21号染色体的数量,符合率为95.74%(45/47)。检出2例21-三体综合征胎儿,与其实际核型相符。结论:PEP结合多个染色体特异性STR位点分型可用于非整倍体异常的无创性产前诊断。

Noninvasive prenatal diagnosis of trisomy 21 using analysis of short tandem repeats

Objective：The purpose of the study is to develop a polymerase chain reaction assay employing short tandem repeats（STRs） for the noninvasive prenatal diagnosis of aneuploidies.Methods：Blood samples were collected from 50 pairs of pregnant women and their partners who came to take genetic counseling.Determined by heamoglobin γ chain staining,fetal nucleated red blood cells（FNRBCs） in maternal blood were picked out by micromanipulation.After primer extension preamplification（PEP）,single candidate cell underwent amplification of three 21 chromosome specific STR loci（D21S11,D21S1411,D21S1412）.The above gene loci were also evaluated in each pair of parents.The result of a fetus was compared with that of its parents,by which the information about corresponding chromosomes of the fetus could be obtained.Results：3 cases among the 50 samples of FNRBCs failed to produce PCR results.In the other 47 cases,the rates of imformativeness of D21S11,D21S1411,D21S1412 were 85.11%、78.72%、76.60% respectively.By combination of the three 21-STRs,the fetal origin of NRBCs could be confirmed in 45 samples and the number of 21 chromosome in fetal cells were also determined with a concordance rate of 95.74%（45/47）.Two babies affected by down syndrome were discerned using this technique,which were verified by fetal real karyotypes.Conclusion：Multiple STR loci analysis based on single cell PEP-PCR can be applied on noninvasive prenatal diagnosis of fetal aneuploidies.