Fetal Medicine Unit, St Michael's Hospital, University Hospitals Bristol NHS Foundation Trust, Bristol, UK.
Prenat Diagn. 2011 Oct;31(10):967-72. doi: 10.1002/pd.2814. Epub 2011 Jul 19.
Free fetal DNA (ffDNA) in the maternal plasma appears to originate mainly from the trophoblast. We tested the hypothesis that ffDNA concentration is increased in multiple pregnancies where trophoblastic mass has been shown to be increased.
Quantitative real-time PCR was used to measure the plasma concentration of DYS14 in singleton and twin pregnancies with one or two male fetuses. Royston and Wright's regression method was used to relate ffDNA to gestational age in singleton controls; z-scores were calculated for the multiple pregnancy subgroups.
Fifty-five singleton and 65 twin pregnancies (36 with one and 29 with two male fetuses) were analysed. There was significantly higher ffDNA concentration in twin pregnancies with two male fetuses compared with pregnancies with one male fetus. In cases with two male fetuses, there was no statistically significant difference between monochorionic and dichorionic pregnancies.
There is higher ffDNA concentration in multiple pregnancies, and this must be taken into account for future quantitative ffDNA applications.
母体血浆中的游离胎儿 DNA（ffDNA）似乎主要来源于滋养层。我们检验了以下假说，即在滋养层质量增加的多胎妊娠中，ffDNA 浓度会升高。
采用实时定量 PCR 方法测量单胎妊娠和双胎妊娠（各有一个或两个男性胎儿）血浆中 DYS14 的浓度。Royston 和 Wright 的回归方法用于将 ffDNA 与单胎对照组的孕周相关联；为多胎妊娠亚组计算 z 分数。
分析了 55 例单胎妊娠和 65 例双胎妊娠（36 例怀有一个男性胎儿，29 例怀有两个男性胎儿）。怀有两个男性胎儿的双胎妊娠的 ffDNA 浓度明显高于怀有一个男性胎儿的妊娠。怀有两个男性胎儿的情况下，单绒毛膜和双绒毛膜妊娠之间无统计学差异。
多胎妊娠中 ffDNA 浓度更高，在未来的定量 ffDNA 应用中必须考虑到这一点。
