目的:探讨应用高通量测序技术对孕妇外周血中胎儿游离DNA进行唐氏综合征筛查的临床应用价值。方法:选择2013年4月至2019年12月在郑州大学第一附属医院遗传与产前诊断中心就诊，行无创产前检测（non-invasive prenatal testing，NIPT）21-三体高风险的1039例孕妇，行羊膜腔穿刺术抽取羊水细胞经荧光定量PCR（quantitative fluorescent polymerase chain reaction，QF-PCR）和染色体核型分析进行验证，探讨经NIPT检测出的21-三体高风险的阳性准确性。结果:1039例NIPT提示为21-三体高风险的孕妇中，经染色体核型分析，886例确诊为21-三体，其阳性预测值（positive predictive value, PPV）为85.27%，包括标准型唐氏综合征核型839例（94.70%）、易位型28例（3.16%）、嵌合型14例（1.58%）、其他异常染色体5例（0.56%）。正常核型153例，假阳性率为14.73%（153/1039）。QF-PCR结果与核型结果相符共计1027例，其准确率为99.32%（1027/1034）。结论:无创DNA检测胎儿21-三体的阳性预测值为85.27%，准确率较高，可以广泛应用于唐氏综合征胎儿出生缺陷的筛查。“,”Objective:To explore the clinical application value of high-throughput sequencing te-chnique in the screening of Down’s syndrome in fetal free DNA in pregnant women.Methods:From Ap-ril 2013 to December 2019, a total of 1039 pregnant women who visited the genetic and prenatal diagnosis center of the first affiliated hospital of Zhengzhou University with non-invasive prenatal testing (NIPT) of trisomy 21 were selected. Quantitative fluorescent polymerase chain reaction (QF-PCR) and chromosome karyotype analysis were performed to verify the high-risk positive accuracy of trisomy 21 detected by non-invasive DNA.Results:Among 1039 pregnant women with a high risk of trisomy 21 in NIPT, chromo-somal karyotype analysis revealed that 886 cases were diagnosed as trisomy 21, and their positive predicti-ve value (PPV) was 85.27%, including 839 cases of standard Down’s syndrome karyotype (94.70%) , 28 ca-ses of translocation type (3.16%) , 14 cases of chimeric type (1.58%) , 5 cases of other abnormal chromosomes (0.56%) . There were 153 normal karyotypes with a false positive rate of 14.73% (153/1039) . The results of QF-PCR were consistent with the results of karyotype in a total of 1027 cases, with an accuracy rate of 99.32% (1027/1034).Conclusion:The non-invasive DNA detection of fetal trisomy 21 has a positive predictive value of 85.27% which is a high, and thus can be widely used in the screening of birth defects of Down’s syndrome fetuses.