应用短串联重复序列快速产前诊断唐氏综合征

Rapid prenatal detection of Down syndrome use short tandem repeats

目的:采用聚合酶链反应技术(PCR),对短串联重复序列(short tandem repeat,STR)进行分析,探讨应用短串联重复序列信息进行21三体产前诊断的可行性。方法:选取21号染色体核心区域21q22.1-22.3及其附近的三个STR(D21S1409,D21S1433,D21S1444),用聚合酶链技术,非变性聚丙烯酰胺凝胶电泳,硝酸银染色技术,对30例正常人外周血及40例羊水样品进行分析。结果:30例正常人在三个STR位点均没有发现三条带。40例羊水样品中检测到三例21三体胎儿,两例与细胞染色体分析结果相符,染色体核型均为"47,XY,+21"。一例为21号染色体关键区域微片段重复,细胞染色体分析结果为"46,XY"。三例21三体和部分21三体多余的染色体和部分片段均来自母亲。其余37例羊水样品检测结果为阴性,细胞染色体分析结果也是阴性。D21S1409、D21S1433、D21S1444三个基因座的杂合度分别为:0.75、0.80、0.78。结论:三个STR均具有高度多态性,在21三体的产前诊断中有较高的应用价值。

Objective ：To develope a PCR-based method to diagnose fetal trisomy 21 directly using short tandem repeat polymorphic markers. Methods： Three short tandem repeats （ STRs ） loci （ D21 S1409, D21 S1433, D21 S1444） in and near the core region （21q22.1-21q22.2） on 21 chromosome of 30 peripheral blood samples of health adults and 40 amniotic fluid samples were analyzed and detected by polymerase chain reaction （PCR） , polyacryl＇amide gel electrophories , and silver staining. Results ： The 30 peripheral blood samples did not show three hands in 3 loci. Three trisomy 21 were detected . Two of them is incoincidence with karyotyping , One showed three bands in the loci of D21S1409 and D21S1433, hut the result of the karyotyping is ＂46XY＂. All of the additional chromosomes and chromosome fragments are gotten from the mothers. 37 of 40 amniotic fluid samples were tested positive by both PCR-STR and karyotyping. The heterozygosities of D21S1409,D21S1433,D21S1444 are 0. 75 ,0. 80,0. 78. Conclusion ：The three locies show high polymorphism ,they are valuable in the diagnosis of fetal trisomy 21.