Effect of labor on postpartum clearance of cell-free fetal DNA from the maternal circulation

Study on the Clinical Value of Noninvasive Prenatal Testing in Screening the Chromosomal Abnormalities of the Fetus in the Elderly Pregnant Women

Introduction

To explore the clinical value of noninvasive prenatal testing (NIPT) in screening the chromosomal abnormalities of the fetus in the elderly pregnant women.

Materials and Methods

Between January 2020 and December 2021, 1949 elderly pregnant women underwent NIPT in our hospital. At the same time, 236 elderly pregnant women received invasive prenatal diagnosis, and the pregnancy outcomes were followed-up.

Results

When NIPT was used for prenatal screening of fetal chromosomal aneuploidy, its diagnostic coincidence rate for trisomy 21 was the highest, with a coincidence rate of 90.00%, and the diagnostic coincidence rate for other chromosomal abnormalities was the lowest, only 22.22%. The sensitivity, specificity, positive predictive rate, and negative predictive rate for T21 by NIPT were 100%, 99.97%, 94.28%, and 100%; for T18 were 100%, 99.92%, 72.22%, and 100%, respectively; and for T13 were 100%, 99.95%, 50%, and 100%, respectively. Patients with high risks according to NIPT results further received invasive prenatal diagnosis, and 18 cases were excluded from the follow-up. For the remaining 1933 cases in the NIPT group, there was an incidence of 2.28% of adverse pregnancy outcomes. For the remaining 234 cases in the Amniocentesis group, there was an incidence of 1.28% of adverse pregnancy outcomes. There was no significant difference between the two groups (P > 0.05). The diagnostic rate of fetal chromosomal abnormalities in pregnant women under 40 years old was about 0.39-0.79%; however, the risk for people over 40 is relatively high at 1.32-4.44%.

Conclusion

The noninvasive prenatal screening of fetal DNA in the second trimester of pregnancy for elderly pregnant women has high application value in the prediction of pregnancy outcome. The high risk of pregnancy can be determined by detecting trisomy 21, 18, and 13 syndromes, and the probability of adverse pregnancy outcome increases.

Current Overview of Osteogenesis Imperfecta

Osteogenesis imperfecta (OI), or brittle bone disease, is a heterogeneous disorder characterised by bone fragility, multiple fractures, bone deformity, and short stature. OI is a heterogeneous disorder primarily caused by mutations in the genes involved in the production of type 1 collagen. Severe OI is perinatally lethal, while mild OI can sometimes not be recognised until adulthood. Severe or lethal OI can usually be diagnosed using antenatal ultrasound and confirmed by various imaging modalities and genetic testing. The combination of imaging parameters obtained by ultrasound, computed tomography (CT), and magnetic resource imaging (MRI) can not only detect OI accurately but also predict lethality before birth. Moreover, genetic testing, either noninvasive or invasive, can further confirm the diagnosis prenatally. Early and precise diagnoses provide parents with more time to decide on reproductive options. The currently available postnatal treatments for OI are not curative, and individuals with severe OI suffer multiple fractures and bone deformities throughout their lives. In utero mesenchymal stem cell transplantation has been drawing attention as a promising therapy for severe OI, and a clinical trial to assess the safety and efficacy of cell therapy is currently ongoing. In the future, early diagnosis followed by in utero stem cell transplantation should be adopted as a new therapeutic option for severe OI.

Non-invasive Prenatal Testing Using Fetal DNA

Non-invasive prenatal diagnosis (NIPD) is based on fetal DNA analysis starting from a simple peripheral blood sample, thus avoiding risks associated with conventional invasive techniques. During pregnancy, the fetal DNA increases to approximately 3-13% of the total circulating free DNA in maternal plasma. The very low amount of circulating cell-free fetal DNA (ccffDNA) in maternal plasma is a crucial issue, and requires specific and optimized techniques for ccffDNA purification from maternal plasma. In addition, highly sensitive detection approaches are required. In recent years, advanced ccffDNA investigation approaches have allowed the application of non-invasive prenatal testing (NIPT) to determine fetal sex, fetal rhesus D (RhD) genotyping, aneuploidies, micro-deletions and the detection of paternally inherited monogenic disorders. Finally, complex and innovative technologies such as digital polymerase chain reaction (dPCR) and next-generation sequencing (NGS) (exhibiting higher sensitivity and/or the capability to read the entire fetal genome from maternal plasma DNA) are expected to allow the detection, in the near future, of maternally inherited mutations that cause genetic diseases. The aim of this review is to introduce the principal ccffDNA characteristics and their applications as the basis of current and novel NIPT.

Noninvasive Approaches to Prenatal Diagnosis: Historical Perspective and Future Directions

The field of prenatal screening and diagnosis has undergone enormous progress over the past four decades. Most of this period has been characterized by gradual improvements in the technical and public health aspects of prenatal screening for Down syndrome. Compared to the direct analysis of fetal cells from amniocentesis or chorionic villus sampling, noninvasive approaches using maternal blood or ultrasound have the great advantage of posing no risk of miscarriage to the pregnancy. Recent advances in molecular genetics and DNA sequencing have revolutionized both the accuracy and the range of noninvasive testing for genetic abnormalities using cell-free DNA in maternal plasma. Many of these advances have already been incorporated into clinical care, including diagnosis of fetal blood group and aneuploidy screening. The accelerated pace of these recent developments is creating not just technical and logistical challenges, but is also magnifying the ethical and public policy issues traditionally associated with this field.

Noninvasive prenatal testing for aneuploidy using cell-free DNA - New implications for maternal health

The rapid global uptake of noninvasive prenatal testing for Down syndrome based on maternal plasma cell-free DNA has provided new data on the interrelationship between cell-free DNA and maternal health. Specific maternal conditions that can affect the performance of noninvasive prenatal testing include obesity, active autoimmune disease and low molecular weight heparin treatment. There is also a growing appreciation of the implications of discordant noninvasive prenatal testing results for maternal health, including unexpected diagnoses of maternal chromosomal conditions, or rarely, occult cancer. The interrelatedness of noninvasive prenatal testing and maternal health mean that the longstanding principles underpinning prenatal screening - voluntary testing, informed decision making, availability of specialist genetic counselling and well-defined clinical pathways - are more important than ever before.

An update on current prenatal testing options: first trimester and noninvasive prenatal testing

Prenatal genetic testing is rapidly evolving and requires that prenatal care providers stay up-to-date with accurate, evidence-based knowledge. Noninvasive prenatal testing (NIPT), first trimester maternal serum markers, and fetal nuchal translucency are the most recently developed screening tests added to the testing repertoire for detection of chromosomal disorders such as trisomy 21 (Down syndrome). NIPT is a new, highly accurate technique that uses maternal serum and is rapidly being introduced as a first trimester screening tool and increasingly being requested by pregnant women. The American College of Obstetricians and Gynecologists recommends that all pregnant women be offered first and second trimester screening options, regardless of risk status, but does not yet recommend NIPT. It is important for prenatal care providers to be aware of and understand these testing options in order to assist women and their families in making well-informed decisions during pregnancy. The purpose of this article is to update midwives and other prenatal care providers on the current prenatal genetic testing options available and how to appropriately offer and discuss them with their clients. We discuss how these tests work; what to do with the results; and most importantly, how to support and communicate accurate information to women and families as they navigate through an increasingly complicated array of testing choices.

Use of cell-free fetal DNA in maternal plasma for noninvasive prenatal screening

Noninvasive prenatal testing (NIPT) using cell-free fetal (cfDNA) offers potential as a screening tool for fetal anomalies. All pregnant women should be offered prenatal screening and diagnostic testing based on current guidelines. Adoption of NIPT in high-risk pregnancies suggests a change in the standard of care for genetic screening; there are advantages to an accurate test with results available early in pregnancy. This accuracy decreases the overall number of invasive tests needed for diagnosis, subjecting fewer pregnancies to the risks of invasive procedures. Women undergoing NIPT need informed consent before testing and accurate, sensitive counseling after results are available.

Effect of labor on plasma concentrations and postpartum clearance of cell-free, pregnancy-associated, placenta-specific microRNAs

OBJECTIVE

This study aimed to investigate the effect of labor on plasma concentrations of cell-free, pregnancy-associated, placenta-specific microRNAs (miRNAs) before and after delivery.

METHOD

In the non-labor group (32 women), cesarean section (C/S) was performed before the beginning of labor. In the labor group (32 women), C/S was performed after the beginning of labor. Plasma concentrations of cell-free, pregnancy-associated, placenta-specific miRNAs (miR-515-3p, miR-517a, miR-517c, and miR-518b) were measured by real-time quantitative PCR. Each miRNA concentration was compared between the non-labor and labor groups.

RESULTS

Before C/S, plasma concentrations of cell-free, pregnancy-associated, placenta-specific miRNAs in the labor group were significantly higher than those in the non-labor group (P = 0.001 for 515-3p, P = 0.002 for 517a, P = 0.001 for 517c, and P = 0.003 for 518b). Twenty-four hours after delivery, plasma concentrations of cell-free, pregnancy-associated, placenta-specific miRNAs in the labor group were significantly higher than those in the non-labor group (P = 0.002 for 515-3p, P = 0.017 for 517a, P = 0.043 for 517c, and P = 0.009 for 518b).

CONCLUSION

The presence of labor affects cell-free, pregnancy-associated, placenta-specific miRNA levels in maternal plasma. Labor also affects postpartum clearance of these miRNAs 24 h after delivery.

Non-Invasive Prenatal Testing Using Cell Free DNA in Maternal Plasma: Recent Developments and Future Prospects

Recent advances in molecular genetic technologies have facilitated non-invasive prenatal testing (NIPT) through the analysis of cell-free fetal DNA in maternal plasma. NIPT can be used to identify monogenic disorders including the identification of autosomal recessive disorders where the maternally inherited mutation needs to be identified in the presence of an excess of maternal DNA that contains the same mutation. In the future, simultaneous screening for multiple monogenic disorders is anticipated. Several NIPT methods have been developed to screen for trisomy. These have been shown to be effective for fetal trisomy 21, 18 and 13. Although the testing has been extended to sex chromosome aneuploidy, robust estimates of the efficacy are not yet available and maternal mosaicism for gain or loss of an X-chromosome needs to be considered. Using methods based on the analysis of single nucleotide polymorphisms, diandric triploidy can be identified. NIPT is being developed to identify a number of microdeletion syndromes including α-globin gene deletion. NIPT is a profoundly important development in prenatal care that is substantially advancing the individual patient and public health benefits achieved through conventional prenatal screening and diagnosis.

Non-invasive prenatal testing for aneuploidy: current status and future prospects

Non-invasive prenatal testing (NIPT) for aneuploidy using cell-free DNA in maternal plasma is revolutionizing prenatal screening and diagnosis. We review NIPT in the context of established screening and invasive technologies, the range of cytogenetic abnormalities detectable, cost, counseling and ethical issues. Current NIPT approaches involve whole-genome sequencing, targeted sequencing and assessment of single nucleotide polymorphism (SNP) differences between mother and fetus. Clinical trials have demonstrated the efficacy of NIPT for Down and Edwards syndromes, and possibly Patau syndrome, in high-risk women. Universal NIPT is not cost-effective, but using NIPT contingently in women found at moderate or high risk by conventional screening is cost-effective. Positive NIPT results must be confirmed using invasive techniques. Established screening, fetal ultrasound and invasive procedures with microarray testing allow the detection of a broad range of additional abnormalities not yet detectable by NIPT. NIPT approaches that take advantage of SNP information potentially allow the identification of parent of origin for imbalances, triploidy, uniparental disomy and consanguinity, and separate evaluation of dizygotic twins. Fetal fraction enrichment, improved sequencing and selected analysis of the most informative sequences should result in tests for additional chromosomal abnormalities. Providing adequate prenatal counseling poses a substantial challenge given the broad range of prenatal testing options now available.

Genomic analysis of fetal nucleic acids in maternal blood

The 15 years since the discovery of fetal DNA in maternal plasma have witnessed remarkable developments in noninvasive prenatal diagnosis. An understanding of biological parameters governing this phenomenon, such as the concentration and molecular size of circulating fetal DNA, has guided its diagnostic applications. Early efforts focused on the detection of paternally inherited sequences, which were absent in the maternal genome, in maternal plasma. Recent developments in precise measurement technologies such as digital polymerase chain reaction (PCR) have allowed the detection of minute allelic imbalances in plasma and have catalyzed analysis of single-gene disorders such as the hemoglobinopathies and hemophilia. The advent of massively parallel sequencing has enabled the robust detection of fetal trisomies in maternal plasma. Recent proof-of-concept studies have detected a chromosomal translocation and a microdeletion and have deduced a genome-wide genetic map of a fetus from maternal plasma. Understanding the ethical, legal, and social aspects in light of such rapid developments is thus a priority for future research.