Cell-Free Nucleic Acids ; blood ; Female ; Humans ; Mosaicism ; Placenta ; Pregnancy

Non-invasive prenatal screening using cell-free fetal DNA (NIPS) has been integrated into the prenatal health care only in a short span of five years, and the guidelines provided by professional bodies have been continuously updated. The American College of Medical Genetics and Genomics has made a statement on NIPS in July, 2016, suggesting that the NIPS can replace conventional screening for Patau, Edwards and Down syndromes in a continuum of gestational age and for any maternal age, except those who are significantly obese. The scope of target diseases of NIPS are also growing. Meanwhile, pre- and post-test counseling for NIPS has put forward a greater challenge for medical professionals.
Cell-Free Nucleic Acids ; analysis ; DNA Copy Number Variations ; Female ; Humans ; Pregnancy ; Prenatal Diagnosis ; methods

Fetal cell free DNA (cfDNA) in maternal blood circulation mainly originates from placental trophoblasts which have dual characteristics of apoptotic cells and the embryo, and can be affected by maternal factors. Pregnancy-related diseases including preeclampsia, gestational diabetes mellitus, preeclampsia, macrosomia and fetal growth restriction can seriously affect maternal health and pregnancy outcome. Early prediction and timely intervention are important means to reduce the risk. Fetal cfDNA and prediction of pregnancy-related diseases have become a hot topicfor current research. This paper reviews the latest progress made in the field.
Cell-Free Nucleic Acids/genetics* ; Female ; Fetus ; Humans ; Placenta ; Pregnancy ; Pregnancy Complications ; Pregnancy Outcome

BACKGROUND: One inevitable shortcoming of non-invasive prenatal screening (NIPS)/cell-free DNA (cfDNA) sequencing is the uninterpretable ("no-call") result, which is mainly caused by an insufficient fetal fraction. This study was performed to investigate the factors associated with a successful second NIPS in these cases and determine the optimal management for women with initial no-call results. METHODS: We retrospectively analyzed the data of women who underwent NIPS with initial no-call results due to an insufficient fetal fraction from 2017 to 2019 in our center. We compared these women's maternal and pregnancy information with the data of women who had attained a successful second NIPS result and women who had received no-call results for a second time. RESULTS: Among the 33,684 women who underwent NIPS, 137 with a no-call result underwent a retest. Comparison between the 87 (63.50%) women with a successful retest and the other 50 (36.50%) women showed a significant difference in both the initial fetal fraction and maternal body mass index (BMI), whereas the other factors showed no significant differences. In addition, with an initial fetal fraction of < 2.00%, the retest success rate was very limited. CONCLUSIONS We identified two major factors associated with a successful NIPS retest: the initial fetal fraction and the maternal BMI. These findings suggest the need for specialized management for this subset of women and would be instructional for the counseling for these women.
Cell-Free Nucleic Acids ; China ; Female ; Fetus ; Humans ; Pregnancy ; Prenatal Diagnosis ; Retrospective Studies

OBJECTIVE: To assess the value of non-invasive prenatal testing based on cfDNA barcode-enabled single-molecule test (cfBEST) for the prenatal diagnosis of oculocutaneous albinism type I in a family. METHODS: Prenatal genetic diagnosis was carried out by using the cfBEST-based method as well as invasive prenatal diagnosis through amniocentesis. The outcome of the pregnancy was followed up. RESULTS: Non-invasive prenatal testing based on cfBEST showed a fetal DNA concentration of 6.6%, with the proportion of c.929_930insC (p.Arg311Lysfs*7) and c.1037-7T>A mutations being 45.7% and 0%, respectively. The posterior frequency of the negative results was 1, suggesting that the fetus carried neither of the two mutations. The result was consistent with that of invasive prenatal diagnosis, and the follow-up found that the fetus was normal. CONCLUSION Non-invasive prenatal testing based on cfBEST can be used to detect maternal and fetal genotypes in maternal cell-free DNA, which is clinically feasible.
Albinism ; Albinism, Oculocutaneous/genetics* ; Amniocentesis ; Cell-Free Nucleic Acids ; Female ; Humans ; Pregnancy ; Prenatal Diagnosis

OBJECTIVE: To assess the value of re-sampling for patients who had failed non-invasive prenatal testing (NIPT) due to low cell-free fetal DNA (cffDNA) fraction. METHODS: Clinical data of 20 387 patients undergoing NIPT test was reviewed. The patients were re-sampled when initial blood test did not yield a result due to cffDNA fraction. The results were analyzed, and the outcome of pregnancy was followed up. RESULTS: Among all samples, 17 (0.08%) had failed to yield a result due to low cffDNA fraction, all of which accepted re-sampling. A result was attained in 16 cases, with a success rate of 94.12%. Only one sample had failed the re-test. CONCLUSION For patients who had failed the initial NIPT due to low cffDNA fraction, re-sampling should be considered with gestational week and ultrasound results taken into consideration.
Aneuploidy ; Cell-Free Nucleic Acids/genetics* ; DNA/genetics* ; Female ; Fetus ; Humans ; Pregnancy ; Prenatal Diagnosis

Monogenic disorders are varied and complex. Its overall incidence is high and the clinical phenotypes differ greatly, causing disability, mental retardation or death. It is an effective strategy to prevent the birth of newborns with monogenic disorders through prenatal screening and diagnosis. Cell-free fetal DNA based non-invasive prenatal testing for monogenic disorders has been applied in clinical practice. The range of diseases being tested is expanding, and the technology is continuously making breakthroughs. This article has provided a review over the research progress made in this field.
Cell-Free Nucleic Acids/genetics* ; DNA/genetics* ; Female ; Fetus ; Humans ; Phenotype ; Pregnancy ; Prenatal Diagnosis

Genomic disorders caused by pathogenic copy number variation (pCNV) have proven to underlie a significant proportion of birth defects. With technological advance, improvement of bioinformatics analysis procedure, and accumulation of clinical data, non-invasive prenatal screening of pCNV (NIPS-pCNV) by high-throughput sequencing of maternal plasma cell-free DNA has been put to use in clinical settings. Specialized standards for clinical application of NIPS-pCNV are required. Based on the discussion, 10 pCNV-associated diseases with well-defined conditions and 5 common chromosomal aneuploidy syndromes are recommended as the target of screening in this consensus. Meanwhile, a standardized procedure for NIPS-pCNV is also provided, which may facilitate propagation of this technique in clinical settings.
Aneuploidy ; Cell-Free Nucleic Acids/genetics* ; Consensus ; DNA Copy Number Variations ; Female ; High-Throughput Nucleotide Sequencing ; Humans ; Pregnancy ; Prenatal Diagnosis

With the development of liquid biopsy technology, plasma cell-free DNA (cfDNA) becomes one of the research hotspots. Whole-genome bisulfite sequencing of plasma cell-free DNA has shown great potential medical applications such as cancer detection. However, the practical stability evaluation is still lacking. In this study, plasma cell-free DNA samples from two volunteers at different time were collected and prepared for sequencing in multiple laboratories. The library preparation strategies include pre-bisulfite, post-bisulfite and regular whole-genome sequencing. We established a set of quality control references for plasma cell-free DNA sequencing data and evaluated practical stability of blood collection, DNA extraction, and library preparation and sequencing depth. This work provided a technical practice guide for the application of plasma cfDNA methylation sequencing for clinical applications.
Cell-Free Nucleic Acids ; DNA Methylation ; High-Throughput Nucleotide Sequencing ; Humans ; Sequence Analysis, DNA ; Sulfites ; Whole Genome Sequencing

OBJECTIVE: To establish a non-invasive method for beta-thalassemia by detecting parental CD41-42 mutation in cell-free DNA derived from maternal plasma with droplet digital PCR (ddPCR). METHODS: Beta-actin gene and beta-thalassemia gene CD41-42 mutation were respectively set as the reference and target sequences. A novel method was established based on Bio-Rad ddPCR technique with specific primers and TaqMan probes for the two genes. The accuracy, sensitivity and detective linearity range of the developed method were evaluated by detection of the target gene gradient concentration samples. The applicability was also evaluated by testing 20 maternal plasma samples. RESULTS: The ddPCR method could accurately detect the beta-thalassemia CD41-42 mutation in cell-free DNA derived from maternal plasma. Within the target sequence concentration ratio of 5.00%-0.50%, the relative errors were all < 0.05, the linear regression equation was Y=1.0101-X-0.0071 and R=0.9994. The results of 20 maternal plasma cell-free DNA samples were all consistent with those of the follow-up testing. CONCLUSION A ddPCR method for detecting parental CD41-42 mutation in cell-free DNA from maternal plasma was developed. The method is simple, rapid, accurate, and can be applied for non-invasive prenatal diagnosis for couples simultaneously carrying the CD41-42 mutation.
Cell-Free Nucleic Acids ; DNA ; blood ; Female ; Humans ; Mutation ; Polymerase Chain Reaction ; Pregnancy ; Prenatal Diagnosis ; methods ; beta-Thalassemia ; diagnosis ; genetics