Fetal DNA in Maternal Plasma in Twin Pregnancies

[摘要] Twin pregnancies have increased in recent years as assisted reproductive technologies have been adapted. The maternal age of women undergoing assisted reproduction is generally higher than that of women with spontaneous pregnancies. This also implies a higher risk of fetal aneuploidies. Furthermore, twin pregnancies are known to have a higher risk of developing complications such as preeclampsia, intrauterine growth retardation, and preterm labor [for a review, see Ref. (1)].Of note is that women who have been trying for years to become pregnant and have finally undergone cumbersome therapeutic interventions could be particularly reluctant to expose their pregnancy to any invasive prenatal diagnostic procedure. Thus, noninvasive screening or diagnostic tests could be particularly welcome in this subset of pregnant women.Noncellular fetal DNA circulating in maternal plasma may represent a suitable source of fetal genetic material that can be obtained noninvasively. Several studies have shown a significantly higher concentration of fetal DNA in maternal plasma in some fetal aneuploidies and placental pathologies (2)(3)(4)(5)(6). Nevertheless, existing data about fetal DNA concentrations in maternal blood under physiologic and pathologic conditions refer only to singleton pregnancies, and reference values for twins are still missing.The origin of the fetal DNA released into maternal plasma is still unclear. Although there is evidence that some of the cell-free fetal DNA in the maternal plasma is derived from blood elements, several authors favor the hypothesis that the majority is derived from the placenta (7)(8). Interestingly, twin pregnancies may present with one or two placentas, and although dizygotic twins must have two placentas, monozygotic twins can be either mono- or bichorionic. It has been reported that monozygotic twins exhibit smaller uteroplacental junctional areas than do …

[学科分类] 过敏症与临床免疫学