Plasma Placental Rna Allelic Ratio Permits Noninvasive Prenatal Chromosomal Aneuploidy Detection

Department of Chemical Pathology, The Chinese University of Hong Kong, Hong Kong, 00, Hong Kong
Nature Medicine (Impact Factor: 27.36). 03/2007; 13(2):218-23. DOI: 10.1038/nm1530
Source: PubMed


Current methods for prenatal diagnosis of chromosomal aneuploidies involve the invasive sampling of fetal materials using procedures such as amniocentesis or chorionic villus sampling and constitute a finite risk to the fetus. Here, we outline a strategy for fetal chromosome dosage assessment that can be performed noninvasively through analysis of placental expressed mRNA in maternal plasma. We achieved noninvasive prenatal diagnosis of fetal trisomy 21 by determining the ratio between alleles of a single-nucleotide polymorphism (SNP) in PLAC4 mRNA, which is transcribed from chromosome 21 and expressed by the placenta, in maternal plasma. PLAC4 mRNA in maternal plasma was fetal derived and cleared after delivery. The allelic ratios in maternal plasma correlated with those in the placenta. Fetal trisomy 21 was detected noninvasively in 90% of cases and excluded in 96.5% of controls.

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    • "The presence of these other nucleic acids permits a much broader array of questions to be addressed (Chim et al., 2008; Hahn et al., 2005; Lo and Chiu, 2011; Lo et al., 2007). "
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    ABSTRACT: Cell-free foetal DNA recently hit the international headlines by facilitating the non-invasive prenatal testing (NIPT) of foetal chromosomal anomalies directly from maternal blood samples. Being largely of placental origin, cell-free foetal DNA may also, however, provide insight into underlying pathological changes in preeclampsia, or the influences of external stresses, such as hypoxia. This analysis may be enhanced by the simultaneous assessment of placenta-derived, cell-free mRNA species. The source of maternal cell-free DNA is not readily apparent, but may involve neutrophil extracellular traps (NETs). The rapid rise in this material following removal of the placenta, especially in preeclampsia, may indicate a rapid transient maternal inflammatory response to placenta-derived debris. Since NETs have recently been shown to promote coagulation, this may provide a link to pregnancy-associated thrombosis or placental infarction. The presence of cell-free, placenta-derived DNA may not be as innocuous as commonly assumed, as it is largely hypomethylated and could, like bacterial DNA, trigger the activation of maternal immune effector cells via interaction with toll-like receptor 9 (TLR9), thereby contributing to an excessive inflammatory response in preeclampsia or preterm labour. Possibly the most fascinating aspect concerning placenta-derived, cell-free nucleic acids is the recent report that placental exosomes loaded with placenta-specific C19MC miRNA species may modulate the antiviral response of maternal immune cells, thereby ensuring foetal well-being.
    Full-text · Article · Apr 2014 · Journal of Reproductive Immunology
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    • "Development of a reliable non-invasive alternative to prenatal diagnostic procedures such as amniocentesis and chorionic villous sampling used to detect fetal aneuploidies has been the goal of numerous scientific groups. Aside from fetal nucleated red blood cells (NRBC, also known as erythroblasts), trophoblasts [1] [2] or fetal cellfree DNA [3] [4] have also been considered as objects for prenatal diagnostics out of maternal blood. Methods used to enrich the rare fetal NRBCs (about 1–8 fetal erythroblasts in 2 mL maternal blood) are amongst others combinations of cell sorting with magnetic particles or flow cytometry [5] [6], density gradient centrifugation [7], selective cell lysis [8], or depletion of unwanted cell populations (5). "
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    ABSTRACT: Continuing efforts in development of non-invasive prenatal genetic tests have focused on the isolation of fetal nucleated red blood cells (NRBCs) from maternal blood for decades. Because no fetal cell-specific antibody has been described so far, the present study focused on the development of monoclonal antibodies (mAbs) to antigens that are expressed exclusively on fetal NRBCs. Mice were immunized with fetal erythroid cell membranes and hybridomas screened for Abs using a multi-parameter fluorescence-activated cell sorting (FACS). Selected mAbs were evaluated by comparative FACS analysis involving Abs known to bind erythroid cell surface markers (CD71, CD36, CD34), antigen-i, galactose, or glycophorin-A (GPA). Specificity was further confirmed by extensive immunohistological and immunocytological analyses of NRBCs from umbilical cord blood and fetal and adult cells from liver, bone marrow, peripheral blood, and lymphoid tissues. Screening of 690 hybridomas yielded three clones of which Abs from 4B8 and 4B9 clones demonstrated the desired specificity for a novel antigenic structure expressed on fetal erythroblast cell membranes. The antigenic structure identified is different from known surface markers (CD36, CD71, GPA, antigen-i, and galactose), and is not present on circulating adult erythroid cells, except for occasional detectability in adult bone marrow cells. The new mAbs specifically bind the same or highly overlapping epitopes of a surface antigen that is almost exclusively expressed on fetal erythroid cells. The high specificity of the mAbs should facilitate development of simple methods for reliable isolation of fetal NRBCs and their use in non-invasive prenatal diagnosis of fetal genetic status.
    Full-text · Article · Jun 2013 · Experimental Cell Research
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    • "However, for fetal aneuploidy detection, noninvasive testing is rather complex, as the chromosome or region of interest is also carried by the mother, and there is only a quantitative difference between the maternal and fetal contribution. The first promising report on noninvasive aneuploidy detection was from Lo et al. in 2007, 5 when using fetal mRNA in the maternal plasma. "
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    ABSTRACT: The goal to noninvasively detect fetal aneuploidies using circulating cell free fetal DNA in the maternal plasma seems to be achieved by the use of massively parallel sequencing (MPS). To date, different MPS approaches exist, all aiming to deliver reliable results in a cost effective manner. The most widely used approach is the whole genome MPS method, in which sequencing is performed on maternal plasma to determine the presence of a fetal trisomy. To reduce costs targeted approaches, only analyzing loci from the chromosome(s) of interest, have been developed. This review summarizes the different MPS approaches, their benefits and limitations and discusses the implications for future noninvasive prenatal testing. This article is protected by copyright. All rights reserved.
    Full-text · Article · Jun 2013 · Prenatal Diagnosis
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