18-三体综合征产前筛查风险值的预测作用

目的探讨18-三体的产前筛查与产前诊断结果的临床应用。方法产前筛查采用时间分辨免疫荧光法检测孕妇血清中甲胎蛋白（AFP）和游离β-人绒毛膜促性腺激素（hCGβ）的浓度,结合孕妇年龄、体重等计算胎儿患18-三体综合征的风险率,产前诊断采用传统的羊水细胞培养染色体核型分析法。结果对145 658例孕妇进行了产前筛查,筛出18-三体高危孕妇（高危截断值为1∶350）588例,阳性率为0.40%。318例产前筛查高危孕妇进行产前诊断发现了15例18-三体患儿,阳性率为4.72%。对高危孕妇的风险值（n）进行了分级：n≥1/50、1/50〉n≥1/100、1/100〉n≥1/150、1/150〉n≥1/200、1/200〉n≥1/250、1/250〉n≥1/300和1/300〉n≥1/350,分成7级后各级的阳性率依次为17.10%、4.44%、0.00%、0.00%、0.00%、0.00%和0.00%。18-三体胎儿的产前筛查高危孕妇和确诊孕妇集中偏向于n值≥1/100,其余n值级别的孕妇高危比例分布相对比较均匀,但阳性率均为0。另有1 220名未作产前筛查的高龄孕妇和477名筛查低危的高龄孕妇也自愿进行了产前诊断,各发现了2例18-三体患儿。结论结合年龄和生化指标计算的18-三体风险指标可以用于孕妇筛查18-三体的风险估计,而且18-三体的高危人群分布和阳性患儿都集中偏向于n值≥1/100,能为遗传咨询提供可靠的依据。

Predictive significance of risk value in prenatal screening for fetal trisomy 18

Objective To investigate the clinical application of prenatal screening and diagnosis for trisomy 18.Methods The concentrations of alpha-fetoprotein（AFP） and free beta-human chorionic gonadotropin（hCGβ） in serum of pregnant women were detected by time-resolved fluoroimmunoassay.The risk rate of fetal trisomy 18 with maternal age,weight and biochemical indicators was calculated.The prenatal diagnosis was carried out by traditional amniotic fluid cell culture karyotype analysis.Results 145 658 pregnant women were enrolled in prenatal screening,and 588 women were detected and showed at high risk for trisomy 18.The positive rate was 0.40%.From 318 pregnant women with high risk for trisomy 18,15 trisomy 18 fetuses were identified,and the positive rate was 4.72%.Screening risk values（n） of trisomy 18 were classified to 7 groups： n≥1/50,1/50n≥1/100,1/100n≥1/150,1/150n≥1/200,1/200n≥1/250,1/250n≥1/300 and 1/300n≥1/350 groups.After grading,the positive rates of 7 groups were 17.10%,4.44%,0.00%,0.00%,0.00%,0.00% and 0.00%,respectively.Trisomy 18 in pregnant women with high risk value and the identified pregnant women were significantly concentrated at n≥1/100.The distribution of pregnant women with high risk value showed average in other n value groups,and the positive rates were all 0.Furthermore,there were 477 low risk and 1 220 without screening advanced age pregnant women accepting prenatal diagnosis voluntarily.Every group found 2 trisomy 18 fetuses.Conclusions Trisomy 18 calculating with age and biochemical indicators can be applied into prenatal risk screening.Trisomy 18 in pregnant women with high risk value and the identified fetuses are significantly concentrated at n≥1/100.These data are helpful for genetic counseling.