正常人群21号染色体上3个位点的多态性及在染色体数目识别中的应用

Polymorphism of three loci In chromosome 21 in normal individuals and prenatal diagnosis for trisome 21 syndrome

目的 探讨正常人群 2 1号染色体 S14 35、 S12 70、 S 3个位点的多态性及三者联合应用于 2 1-三体综合征产前诊断中的可行性。 方法 利用 3个位点的四聚核苷酸重复序列多态性 ,用生物素标记聚合酶链反应 ( PCR) ,扩增 DNA ,检测沈阳地区 6 0例孕中期 ( 18～ 2 2周 )孕妇羊水。 结果 2 1号染色体 S14 35、 S12 70和 S 3个位点杂合率分别为 80 .0 0 % ( 4 8/ 6 0 )、 78.33% ( 4 7/ 6 0 )、83.33% ( 5 0 / 6 0 ) ;3个位点均纯合占 0 .75 %。 结论 正常人群 2 1号染色体上均出现 3个位点的四聚核苷酸重复序列 ,应用 PCR方法可方便和快捷地在 2 4 h内完成 2 1-三体综合征的产前诊断工作。

Objective To study the polymorphism of D21S1435、D21S1270 and D21S in chromosome 21,and to evaluate the application on prenatal diagnosis for Downs syndrome. Methods Amniotic fluid samples from 60 pregnant women in second trimester (18 22 weeks gestation) in Shenyang were detected with polymorphism analysis of tetranucleotide repeats at 3 loci.PCR amplified with biotin labeling. Results Tetranucleotide repeats at 3 loci in chromosome 21 presented in normal individuals.Heterozygous at 3 loci were 80 00 %、78 33 % and 83 33 % respectively,homozygous at 3 loci were about 0 75 %. Conclusion Combination of polymorphism analysis at 3 loci may improve the prenatal diagnosis for Down's syndrome.