Lack of dramatic enrichment of fetal DNA in maternal plasma by formaldehyde treatment.

variations in detection sensitivity and quantification of fetal DNA concentrations were noted among laboratories very familiar with real-time PCR technology (21). Further studies will be needed to clarify this issue in addition to the continued exploration of other strategies for the investigation of complex fetal genetic traits by analysis of maternal plasma. These strategies may include the enrichment of fetal sequences by size-fractionation of plasma DNA (22, 23) or the use of mass spectroscopy (24), which has recently been shown to permit reliable detection of fetal point mutations. Prediction of fetal D status from maternal plasma: introduction of a new noninvasive fetal RHD geno-typing service. al. Elevation of both maternal and fetal extracellular circulating deoxyribo-nucleic acid concentrations in the plasma of pregnant women with pre-eclampsia. concentration of circulating corticotropin-releasing hormone mRNA in maternal plasma is increased in preeclampsia. fetal DNA in the plasma of pregnant women with severe fetal growth restriction. Relationship between severity of hyperemesis gravidarum and fetal DNA concentration in maternal plasma. in maternal plasma is elevated in pregnancies with aneuploid fetuses. of human chorionic gonadotropin ␤-subunit mRNA concentrations in maternal serum in aneuploid pregnancies: a feasibility study. alW. Plasma ␥-globin gene expression suggests that fetal hematopoietic cells contribute to the pool of circulating cell-free fetal nucleic acids during pregnancy. The levels of circulatory cell free fetal DNA in maternal plasma are elevated prior to the onset of preeclampsia. Interlaboratory comparison of fetal male DNA detection from common maternal plasma samples by real-time PCR. separation of circulatory DNA in maternal plasma permits ready detection of fetal DNA polymorphisms. detection of a fetal point mutation for achondroplasia by the use of size-fractionated circulatory DNA in maternal plasma. Chan AY, et al. MS analysis of single-nucleotide differences in circulating nucleic acids: application to non-invasive prenatal diagnosis. The discovery of fetal DNA in maternal plasma has opened up new possibilities for noninvasive prenatal diagnosis (1– 6). A recent report (7) indicated that the proportion of fetal DNA in maternal plasma can be dramatically enriched through the adoption of a blood-processing protocol involving the addition of formalde-hyde to maternal blood samples. Dhallan et al. (7) suggested that these observations might be the result of several factors, including a reduction in background maternal DNA by minimization of maternal cell lysis through formaldehyde-mediated cell membrane stabilization and the use of a gentle centrifugation protocol, as well as the preservation of fetal DNA through nuclease …