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目的:探讨孕中期血清筛查联合无创性产前基因诊断对降低唐氏综合征患儿出生率的意义。方法:采用时间分辨免疫荧光法检测孕14~20+6周1 242名孕妇血清甲胎蛋白和游离β-人绒毛膜促性腺激素水平,应用Multicalc软件计算唐氏综合征风险值。唐氏综合征高风险切割值为1∶270,≥1∶270为高风险孕妇;18-三体综合征高风险切割值为1∶350,≥1∶350为18-三体综合征高风险孕妇。孕妇均抽取静脉血4~20 mL行胎儿细胞富集分离与鉴定,对胎儿有核红细胞进行单细胞基因分析,并应用基因扫描技术对短串联重复序列位点基因片段进行检测。结果:血清甲胎蛋白+游离β-人绒毛膜促性腺激素筛查出高风险孕妇35名,其中唐氏综合征高风险20名,18-三体综合征高风险9名,神经管缺陷高风险6名,阳性率2.8%。20名唐氏综合征高风险孕妇中,21号染色体短串联重复序列位点为三体图谱型6名,其中1∶1∶1基因型4名,2∶1基因型2名;1名2∶1基因型孕妇自然流产,对流产胎体进行细胞核分型,确诊为唐氏综合征,余5名活产新生儿经细胞核型分析确诊为唐氏综合征。1 207名低风险孕妇基因扫描均为正常二倍体1∶1基因型。结论:唐氏综合征血清筛查联合无创性产前基因诊断,可提高唐氏综合征产前诊断率,降低唐氏综合征患儿出生率。
Objective: To investigate the significance of the second trimester serum screening in combination with noninvasive prenatal diagnosis to reduce the birth rate in children with Down Syndrome. Methods: The levels of serum alpha-fetoprotein and free beta-human chorionic gonadotropin in 1242 pregnant women at 14-20 + 6 weeks were detected by time-resolved immunofluorescence. The risk of Down’s syndrome was calculated by Multicalc software. Down’s syndrome high risk cut value of 1: 270, ≥ 1: 270 for high-risk pregnant women; 18-trisomy syndrome high risk cut value of 1: 350, ≥ 1: 350 for the 18-trisomy syndrome high risk Pregnant women. Pregnant women were drawn venous blood 4 ~ 20 mL line of fetal cell enrichment and identification of fetal nucleated erythrocytes single-cell gene analysis, and application of gene-scanning technology for short tandem repeat loci gene fragments were detected. Results: Serum alpha-fetoprotein + free beta-human chorionic gonadotropin was screened out for 35 high-risk pregnant women, including 20 with Down’s syndrome, 9 with 18-trisomy syndrome, and high neural tube defects The risk of 6, the positive rate of 2.8%. Among the 20 high risk pregnant women with Down’s syndrome, the chromosome 21 short tandem repeat loci were 6 in the trisomic map, of which 4 were in the 1: 1: 1 genotype and 2 were in the 2: 1 genotype; 1 was 2 : 1 Genotypes of pregnant women spontaneous abortion, abortion fetal cell nuclei typing, diagnosed as Down’s syndrome, more than 5 live births confirmed by neonatal karyotype analysis of Down’s syndrome. 1 207 low-risk pregnant women gene scan are normal diploid 1: 1 genotype. Conclusion: Down’s syndrome serum screening combined with noninvasive prenatal gene diagnosis can improve the prenatal diagnosis of Down Syndrome and reduce the birth rate of children with Down’s syndrome.