无创产前筛查中胎儿游离DNA比例的影响因素分析

Analysis of influencing factors in fetal cell-free DNA ratio during non-invasive prenatal screening

目的分析无创产前筛查(NIPS)中影响胎儿游离DNA(cffDNA)比例的因素,探讨cffDNA比例偏低造成NIPS检测失败的原因,为不同孕妇制订个体化的产前遗传学检测方案提供参考。方法对4268例进行NIPS检测的孕妇跟踪随访至胎儿出生,并对孕妇的相关资料进行收集,分析孕妇孕周、体质量指数(BMI)、年龄、妊娠单双胎、标本运输时间与血浆cffDNA比例的相关性,并对cffDNA比例<3.5%的标本重新采血后进行检测,探讨标本重新采血的可行性。结果cffDNA比例与孕周呈正相关(r=0.113,P<0.05)。cffDNA比例与孕妇BMI和年龄呈负相关(r=-0.261、-0.088,P<0.05)。妊娠单双胎和标本运输时间与cffDNA比例无相关性(P>0.05)。cffDNA比例<3.5%的孕妇经重新采血后检测,50%的孕妇能够得到检测结果。结论cffDNA比例与孕周呈正相关,与孕妇BMI、年龄呈负相关。临床可根据筛查对象的BMI、年龄、孕周制订个体化的采血时间,对于肥胖、年龄较大的孕妇可适当将筛查孕周后移。

Objective To analyze the factors affecting the cell-free fetal DNA(cffDNA)in the non-invasive prenatal screening(NIPS),and to investigate the further cause of NIPS detection failure due to low cffDNA ratio to provide references for formulating the individualized prenatal genetic detection scheme for different pregnant women.Methods A total of 4268 pregnant women undergoing NIPS were followed up to the birth of the fetus,and the pregnant women related data were collected.The gravida′s gestational week,body mass index(BMI),age,single and twin pregnancy,sample transport times and plasma cffDNA ratio conducted the correlation analysis.Moreover the samples of cffDNA ratio<3.5%conducted the detection after the second blood collection to investigate the feasibility of the blood sample re-collection.Results The cffDNA ratio showed the positive correlation with the gestational week(r=0.113,P<0.05).cffDNA ratio was negatively correlated with BMI and age of the pregnant women(r=-0.261,-0.088,P<0.05).No correlation between the single fetus,twin fetus and sample transport time with the cffDNA ratio was not be found(P>0.05).In the detection after blood re-collection in the pregnant women with cffDNA<3.5%,50%of pregnant women could obtain the detection results.Conclusion The cffDNA ratio has the positive correlation with the gestation weeks and negatively correlated with the BMI and age of the pregnant women.In clinical application,the individualized blood collection time can be formulated according to the BMI,age and gestational weeks of the screening subjects.For the pregnant women with obesity and older age,the screening gestational week can be appropriately delayed.