Abstract：
OBJECTIVE: To explore the cause of inconsistency between the results of trisomy 7 by expanded non-invasive prenatal testing (NIPT-PLUS) and trisomy 18 by prenatal diagnosis.
METHODS: A pregnant woman who received genetic counseling at Jiaozuo Maternal and Child Health Care Hospital on July 5, 2020 was selected as the study subject. NIPT-PLUS, systematic ultrasound and interventional prenatal testing were carried out. The middle segment and root of umbilical cord, center and edge of the maternal and fatal surface of the placenta were sampled for the validation by copy number variation sequencing (CNV-seq).
RESULTS: The result of NIPT-PLUS indicated that the fetus has trisomy 7. Systematic ultrasound has shown multiple malformations including atrioventricular septal defect, horseshoe kidney, and rocker-bottom feet. However, QF-PCR, chromosomal karyotyping analysis, and CNV-seq of amniotic fluid samples all showed that the fetus was trisomy 18. Validation using multiple placental samples confirmed that the middle segment of the umbilical cord contains trisomy 18, the center of the placenta contained trisomy 7, and other placental sites were mosaicism for trisomy 7 and trisomy 18. Notably, the ratio of trisomy 18 became lower further away from the umbilical cord.
CONCLUSIONS: The false positive results of trisomy 7 and false negative trisomy 18 by NIPT-PLUS was probably due to the existence of placental mosaicism. Strict prenatal diagnosis is required needed aneuploidy is detected by NIPT-PLUS to exclude the influence of placental mosaicisms.
METHODS: A pregnant woman who received genetic counseling at Jiaozuo Maternal and Child Health Care Hospital on July 5, 2020 was selected as the study subject. NIPT-PLUS, systematic ultrasound and interventional prenatal testing were carried out. The middle segment and root of umbilical cord, center and edge of the maternal and fatal surface of the placenta were sampled for the validation by copy number variation sequencing (CNV-seq).
RESULTS: The result of NIPT-PLUS indicated that the fetus has trisomy 7. Systematic ultrasound has shown multiple malformations including atrioventricular septal defect, horseshoe kidney, and rocker-bottom feet. However, QF-PCR, chromosomal karyotyping analysis, and CNV-seq of amniotic fluid samples all showed that the fetus was trisomy 18. Validation using multiple placental samples confirmed that the middle segment of the umbilical cord contains trisomy 18, the center of the placenta contained trisomy 7, and other placental sites were mosaicism for trisomy 7 and trisomy 18. Notably, the ratio of trisomy 18 became lower further away from the umbilical cord.
CONCLUSIONS: The false positive results of trisomy 7 and false negative trisomy 18 by NIPT-PLUS was probably due to the existence of placental mosaicism. Strict prenatal diagnosis is required needed aneuploidy is detected by NIPT-PLUS to exclude the influence of placental mosaicisms.
摘要：
目的：探讨扩展非侵入性产前检测（NIPT-PLUS）7三体与产前诊断18三体的结果不一致的原因。
方法：选择2020年7月5日在焦作市妇幼保健院接受遗传咨询的孕妇作为研究对象。NIPT-PLUS,进行了系统的超声和介入性产前检测。脐带的中段和根，通过拷贝数变异测序(CNV-seq)对母体和致命胎盘表面的中心和边缘进行取样验证.
结果：NIPT-PLUS的结果表明胎儿具有三体7。系统超声显示多种畸形，包括房室间隔缺损，马蹄肾,和摇杆底部的脚。然而,QF-PCR,染色体核型分析，羊水样本的CNV-seq均显示胎儿为18三体。使用多个胎盘样本进行的验证证实，脐带的中段包含18三体，胎盘的中心包含7三体，而其他胎盘部位对于7三体和18三体是镶嵌性的。值得注意的是,远离脐带，18三体的比例变得更低。
结论：NIPT-PLUS对7三体和18三体的假阳性结果可能是由于胎盘镶嵌的存在。需要严格的产前诊断，需要通过NIPT-PLUS检测到非整倍体，以排除胎盘镶嵌的影响。
方法：选择2020年7月5日在焦作市妇幼保健院接受遗传咨询的孕妇作为研究对象。NIPT-PLUS,进行了系统的超声和介入性产前检测。脐带的中段和根，通过拷贝数变异测序(CNV-seq)对母体和致命胎盘表面的中心和边缘进行取样验证.
结果：NIPT-PLUS的结果表明胎儿具有三体7。系统超声显示多种畸形，包括房室间隔缺损，马蹄肾,和摇杆底部的脚。然而,QF-PCR,染色体核型分析，羊水样本的CNV-seq均显示胎儿为18三体。使用多个胎盘样本进行的验证证实，脐带的中段包含18三体，胎盘的中心包含7三体，而其他胎盘部位对于7三体和18三体是镶嵌性的。值得注意的是,远离脐带，18三体的比例变得更低。
结论：NIPT-PLUS对7三体和18三体的假阳性结果可能是由于胎盘镶嵌的存在。需要严格的产前诊断，需要通过NIPT-PLUS检测到非整倍体，以排除胎盘镶嵌的影响。
