Fetal Down Syndrome Research Articles

Role of Fetal Second Trimester 2D Ultrasound Facial Parameters in Down Syndrome Detection

Abstract Introduction Down syndrome (DS) is the most common genetic cause of intellectual disability in humans. Various screening techniques are available, including the detection of facial characteristics of DS fetuses by prenatal ultrasonographic markers. Very few studies have tested the predictive validity of the markers in the Indian population. Objective This article determines the role of second trimester ultrasound in predicting DS using facial markers, namely, nasal bone length (NBL), prenasal thickness (PNT), NBL/PNT ratio, and PNT/NBL ratio in the Indian population Materials and Methods This prospective observational study recruited singleton pregnant women at 14 to 28 weeks of gestation with no comorbidities. Women with maternal disorders, abnormal amniotic fluid, and fetal structural anomalies were excluded. Three images of the midsagittal plane were obtained during a routine anomaly or well-being scan. The single “best” image was used for analysis. Scatter plots with regression lines and percentile curves for each gestation were created. Developed nomograms and scattered plots were validated by recruiting DS fetuses (diagnosed by amniocentesis and fetal karyotype). Results This study included 450 normal fetuses for developing nomograms, which were verified by matching 45 DS fetuses. The diagnostic accuracy of NBL, PNT, NBL/PNT ratios and PNT/NBL ratios was found to be 94, 99, 95, and 94.8, respectively. Sensitivity and specificity were found to be 51.11, 42.42, 48.89, 65.4 and 99, 96, 99.56, and 96.7 for NBL, PNT, NBL/PNT ratio, and PNT/NBL ratio, respectively. False negative rate and false positive rate were 38.89, 57.58, 51.11, 34.6 and 1, 4, 0.44, 3.3 for NBL, PNT, NBL/PNT ratio, PNT/NBL ratio, respectively. Conclusion High diagnostic accuracy was found for PNT, followed by NBL/PNT ratio, PNT/NBL ratio, and NBL. However, considering sensitivity and specificity markers together, we found the NBL/PNT ratio as a good diagnostic marker in predicting DS. Furthermore, the NBL/PNT ratio performs slightly better than its inverse counterpart (PNT/NBL ratio) for detecting DS fetuses, primarily because it produced less false positive cases.

Absent or hypoplastic nasal bone: What to tell the prospective parents?

Absent or hypoplastic nasal bone (AHNB) on first or second-trimester ultrasonography (USG) is an important soft marker of Down syndrome. However, due to its varied incidence in euploid and aneuploid fetuses, there is always a dilemma of whether to go for invasive fetal testing for isolated AHNB. This study aims to assess outcomes specifically within the context of Indian ethnicity women. This was a prospective observational study. All patients who reported with AHNB in the first- or second-trimester USG were included. Genetic counseling was done, and noninvasive and invasive testing was offered. Chromosomal anomalies were meticulously recorded, and pregnancy was monitored. The incidence of AHNB in our study was 1.16% (47/4051). Out of 47 women with AHNB, the isolated condition was seen in 32 (0.78%) cases, while AHNB with structural anomalies was seen in nine cases (0.22%). Thirty-nine women opted for invasive testing. Six out of 47 had aneuploidy (12.7%), while two euploid cases (4.25%) developed nonimmune hydrops. The prevalence of Down syndrome in fetuses with AHNB was 8.5% (4/47) and 0.42% (17/4004) in fetuses with nasal bone present. This difference was statistically significant (p = .001). The results indicate that isolated AHNB cases should be followed by a comprehensive anomaly scan rather than immediately recommending invasive testing. However, invasive testing is required when AHNB is associated with other soft markers or abnormalities. As chromosomal microarray is more sensitive than standard karyotype in detecting chromosomal aberrations, it should be chosen over karyotype.

Micro-CT Imaging of Tracheal Development in Down Syndrome and Non-Down Syndrome Fetuses.

Down syndrome (DS) is associated with airway abnormalities including a narrowed trachea. It is uncertain whether this narrowed trachea in DS is a consequence of deviant fetal development or an acquired disorder following endotracheal intubation after birth. This study aimed to compare the tracheal morphology in DS and non-DS fetuses using microfocus computed tomography (micro-CT). Twenty fetal samples were obtained from the Dutch Fetal Biobank and divided into groups based on gestational age. Micro-CT images were processed to analyze tracheal length, volume, and cross-sectional area (CSA). Mean tracheal length and tracheal volume were similar in DS and non-DS fetuses for all gestational age groups. Mean, minimum, and maximal tracheal CSA were statistically significantly increased in the single DS fetus in the group of 21-24 weeks of gestation, but not in other gestational age groups. In 90% of all studied fetuses, the minimum tracheal CSA was located in the middle third of the trachea. Tracheal development in DS fetuses was similar to non-DS fetuses between 13 and 21 weeks of gestation. This suggests that the narrowed tracheal diameter in DS children may occur later in fetal development or results from postnatal intubation trauma. The narrowest part of the trachea is in majority of DS and non-DS fetuses the middle third. 3 Laryngoscope, 134:4389-4395, 2024.

SARS-CoV-2 Infection Increases High Risk Rate of Down Syndrome Screening Test by Reducing Alpha-Fetoprotein.

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been a significant global health issue in recent years. Numerous studies indicate that COVID-19 during pregnancy is associated with an increased likelihood of pregnancy complications. Additionally, pregnancy itself is known to elevate the risk of severe SARS-CoV-2 infection. To explore the potential impact of SARS-CoV-2 infection on the probability of Down syndrome in fetuses, we conducted serological testing of Down syndrome markers in pregnant women who had contracted the virus. Serological experiments were conducted utilizing a particle chemiluminescence test. The cohort of pregnant women was categorized into three groups: a control group with no infection, a group infected with SARS-CoV-2 Omicron within the first six weeks of gestation, and a group infected beyond the sixth week of gestation. In the group of individuals infected within 6 gestational weeks, the infection resulted in a decrease in alpha-fetoprotein (AFP) levels and a higher positive rate of Down syndrome screening tests (p ˂ 0.05). However, in this study, SARS-CoV-2 infection did not lead to an increase in the occurrence of Down syndrome in the fetus. The positive rate of women infected beyond 6 gestational weeks was slightly higher than the non-infected group (6.2% vs. 5.7%), but these differences were not statistically significant (p > 0.05). Within the group infected beyond 6 gestational weeks, there was, compared to the control group, a decrease in free beta human chorionic gonadotropin (β-hCG) levels (p < 0.05). This study presents a novel investigation into the impact of SARS-CoV-2 infection on AFP and β-hCG levels. It has been observed that pregnant women who contract SARS-CoV-2 may exhibit an increased likelihood of positive results in serum tests conducted for Down syndrome screening. However, it is important to note that the occurrence of Down syndrome in the developing fetus does not appear to be elevated. To validate these findings, additional research involving larger and diverse cohorts is necessary.

Результати комплексних пренатальних обстежень за наявності дисбалансу хромосоми 21 у плода

Purpose - to characterize the cases of chromosome 21 imbalance in fetuses of high-risk pregnant women, to describe prenatal cytogenetic diagnosis and associated ultrasound findings - structural anomalies and soft markers. Materials and methods. The results of complex prenatal examination of high-risk pregnant women in the Department of Fetal Medicine of the SI “Institute of Pediatrics, Obstetrics and Gynecology named after academician O.M. Lukyanova of the NAMS of Ukraine” during 5 years period were analyzed: results of ultrasound and cytogenetic exams of 200 cases of chromosome 21 imbalance in the fetus. Results. Among 4,748 prenatal cytogenetic testing of fetuses of high-risk women abnormal karyotypes with an imbalance of chromosome 21 were found in 200 (4.21%) cases. In the majority of cases Down's syndrome (DS) was diagnosed (n=199; 99.5%), in 1 (0.2%) case - deletion of chromosome 21. In DS, regular trisomy of chromosome 21 was found in 191 (95.97%) cases, translocant forms - in 5 (2.51%) cases, in 1 (0.5%) case there was there was an additional sex chromosome, and in 1 (0.5%) - a variant with two cell lines. In 1 (0.5%) case limited placental mosaicism was present, with a false negative result that required verification by the analysis of fetal lymphocytes obtained during cordocentesis. Advanced maternal age (≥35 years) was registered in less than half of fetal DS cases (n=92/199, 46.2%). The main indications for invasive procedures and their types are described. It was demonstrated that ultrasound findings (structural anomalies and/or “soft” markers for chromosomal pathology) were present in 78% of fetal chromosome 21 imbalance; nevertheless in 22% ultrasound findings were absent, and the indication for invasive procedures were advanced maternal age or isolated changes of biochemical markers. Conclusions. Chromosome 21 imbalance in fetuses is mainly represented by trisomy, cases of chromosome 21 deletion are extremely rare. Targeted ultrasound examination is important for screening and diagnosis of fetal chromosomal abnormalities. High-risk pregnant women shouldn’t be reassured in case of “normal” ultrasound exam results. Under certain conditions, it is advisable to perform placental biopsy in the II trimester of pregnancy, but only in specialized tertiary centers or departments. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of the participating institution. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the authors.

Single-cell landscape analysis reveals systematic senescence in mammalian Down syndrome.

Down syndrome (DS), which is characterized by various malfunctions, is the most common chromosomal disorder. As the DS population continues to grow and most of those with DS live beyond puberty, early-onset health problems have become apparent. However, the cellular landscape and molecular alterations have not been thoroughly studied. This study utilized single-cell resolution techniques to examine DS in humans and mice, spanning seven distinct organs. A total of 71 934 mouse and 98 207 human cells were analyzed to uncover the molecular alterations occurring in different cell types and organs related to DS, specifically starting from the fetal stage. Additionally, SA-β-Gal staining, western blot, and histological study were employed to verify the alterations. In this study, we firstly established the transcriptomic profile of the mammalian DS, deciphering the cellular map and molecular mechanism. Our analysis indicated that DS cells across various types and organs experienced senescence stresses from as early as the fetal stage. This was marked by elevated SA-β-Gal activity, overexpression of cell cycle inhibitors, augmented inflammatory responses, and a loss of cellular identity. Furthermore, we found evidence of mitochondrial disturbance, an increase in ribosomal protein transcription, and heightened apoptosis in fetal DS cells. This investigation also unearthed a regulatory network driven by an HSA21 gene, which leads to genome-wide expression changes. The findings from this study offer significant insights into the molecular alterations that occur in DS, shedding light on the pathological processes underlying this disorder. These results can potentially guide future research and treatment development for DS.

COMBINED FIRST TRIMESTER SCREENING FOR FETAL DOWN SYNDROME AT THE SPLIT UNIVERSITY HOSPITAL CENTER: A SEVEN-YEAR EXPERIENCE.

The aim of this study was to present the results and to explore the success of combined screening at the Split University Hospital Center. A cross-sectional retrospective study was performed, including all pregnant women who underwent combined screening at the Split University Hospital Center from 2011 to 2017. Data were collected from the hospital archives. During the research period, a total of 6898 pregnant women underwent combined screening. With the high risk cut-off value set at 1:250, the sensitivity of combined screening was 81.0% and specificity 96.8% (AUC 0.929, 95% CI 0.859-1.000; p<0.001). The mean value of a priori risk of Down syndrome based on age was higher than the one calculated by combined screening (1:487.57 vs. 1:13216.9; p<0.001). The number of women who were a priori at a high risk of Down syndrome was significantly higher than the number of those at a high risk based on combined screening results (1457 vs. 239; p<0.001). With the increase in women's age, a statistically significant increase was detected in the mean value of a priori risk of Down syndrome, as well as in the risk based on combined screening results (p<0.001). Combined screening detected a high risk in 8.09% (118/1457) of pregnant women a priori at a high risk of Down syndrome, as well as in 2.22% (121/5441) of pregnant women a priori at a low risk of it. Thus, combined screening placed 121 pregnant women a priori at a low risk in the high-risk group. Down syndrome was subsequently confirmed in 17 (14.05%) women. Analysis of the combined screening results confirmed the validity of using the said fetal Down syndrome screening method in the study population of pregnant women.

Cost-Benefit Analysis of Down Syndrome Screening in Iran

Background: Down syndrome (DS) screening has been integrated into prenatal care programs in Iran. Objectives: Using cost-benefit analysis (CBA) method, this study aimed to evaluate the economic aspects of combined first trimester screening in Iran. Methods: The population of this descriptive cross-sectional study included all pregnant women in Tehran, Iran. A decision tree model was used to determine the costs and benefits of diagnosing and averting a DS fetus through screening. Direct and indirect costs of diagnosis and the incremental living costs of DS children in 2019 were calculated from societal perspective and compared with each other. Results: The cost of identifying a fetus with DS in Iran is approximately equal to 611 million Tomans (about 25,000 USD), and the incremental living cost of DS children (benefits) was about 34 million Tomans (about 2,270 USD). The net monetary benefit was negative due to the lower incremental living cost of a DS child than the cost of finding the affected fetus. Conclusions: The result of this study showed the screening tests for DS needs revision and consideration in Iran, and due to the high cost of screening, coverage with insurance organization is necessary.

Amniotic fluid and urine metabolomic alterations associated with pregnant women with Down syndrome fetuses

Background Down syndrome (DS) is a chromosomal disorder caused by a third copy of all or part of chromosome 21. Clinical observations and preclinical studies both suggest that DS may be associated with significant metabolic and bioenergetic alterations. But the metabolic alterations in pregnant women carrying DS fetuses still remains unclear. In this study, we investigated the characteristic metabolomics and lipidomics changes during fetal development of DS. Methods The AF and random urine specimens were selected from 20 pregnant women carrying DS fetuses and 20 pregnant women carrying healthy fetuses. The diagnosis of DS was screened according to chromosome karyotype analysis, and untargeted metabolomic and lipidomic analyses were performed. Results Through the analyses of AF, 308 differential metabolites were selected between DS and controls. The metabolites with significant changes mainly involved lipid molecules, organic acids, nucleotides and carbon. Further analysis of lipidomics showed 64 differential metabolites, mainly involving glycerides, sphingolipids and glycerolipids. As for urine metabolomic and lipidomic analyses, there existed consistent metabolites with AF, but the number was much less. Conclusions Compared with the controls, carbon metabolism, amino acid metabolism, glyceride metabolism, sphingolipid metabolism and glycerophospholipid metabolism were significantly changed in DS cases. In addition, characterized biomarkers in AF and urine were screened for DS diagnosis, and these metabolites were mainly involved in energy metabolism and liver dysfunction. This finding may help improve the efficiency of prenatal screening for DS.

Immunoassay-Amplified Responses Using a Functionalized MoS2-Based SPR Biosensor to Detect PAPP-A2 in Maternal Serum Samples to Screen for Fetal Down's Syndrome.

BackgroundDue to educational, social and economic reasons, more and more women are delaying childbirth. However, advanced maternal age is associated with several adverse pregnancy outcomes, and in particular a high risk of Down’s syndrome (DS). Hence, it is increasingly important to be able to detect fetal Down’s syndrome (FDS).MethodsWe developed an effective, highly sensitive, surface plasmon resonance (SPR) biosensor with biochemically amplified responses using carboxyl-molybdenum disulfide (MoS2) film. The use of carboxylic acid as a surface modifier of MoS2 promoted dispersion and formed specific three-dimensional coordination sites. The carboxylic acid immobilized unmodified antibodies in a way that enhanced the bioaffinity of MoS2 and preserved biorecognition properties of the SPR sensor surface. Complete antigen pregnancy-associated plasma protein-A2 (PAPP-A2) conjugated with the carboxyl-MoS2-modified gold chip to amplify the signal and improve detection sensitivity. This heterostructure interface had a high work function, and thus improved the efficiency of the electric field energy of the surface plasmon. These results provide evidence that the interface electric field improved performance of the SPR biosensor.ResultsThe carboxyl-MoS2-based SPR biosensor was used successfully to evaluate PAPP-A2 level for fetal Down’s syndrome screening in maternal serum samples. The detection limit was 0.05 pg/mL, and the linear working range was 0.1 to 1100 pg/mL. The women with an SPR angle >46.57 m° were more closely associated with fetal Down’s syndrome. Once optimized for serum Down’s syndrome screening, an average recovery of 95.2% and relative standard deviation of 8.5% were obtained. Our findings suggest that carboxyl-MoS2-based SPR technology may have advantages over conventional ELISA in certain situations.ConclusionCarboxyl-MoS2-based SPR biosensors can be used as a new diagnostic technology to respond to the increasing need for fetal Down’s syndrome screening in maternal serum samples. Our results demonstrated that the carboxyl-MoS2-based SPR biosensor was capable of determining PAPP-A2 levels with acceptable accuracy and recovery. We hope that this technology will be investigated in diverse clinical trials and in real case applications for screening and early diagnosis in the future.

Amniotic fluid metabolic fingerprinting indicated metabolites which may play a role in the pathogenesis of foetal Down syndrome - a preliminary report.

Down syndrome is the most common human chromosomal aberration. It is commonly known that it is a genetic- based disease, but still, pathomechanisms which lead to observed disorders have not been explained. The objective of this study was to determine the metabolic fingerprinting of the amniotic fluid women carrying foetuses with Down syndrome (DS). The study and control groups consisted of women who underwent routine amniocentesis between the 15th and 18th week of gestation. After analysis of the karyotyping results, 13 women with foetal DS were chosen. For the control group, 13 healthy patients with uncomplicated pregnancies who delivered healthy newborns at term was selected. Amniotic fluid was analyzed using liquid chromatography combined with high resolution mass spectrometry. In the amniotic fluid of women with foetal DS compared to patients with healthy foetuses, we reported significant differences in the level of four metabolites: methylhistidine, hexanoylcarnitine, diacetylspermine and p-cresol sulfate which may be connected with improper development of nervous system and muscles. We detected bacterial metabolite, which support the latest thesis about non-sterile intrauterine environment. Based on our findings, we hypothesise that differences in the level of four metabolites in the amniotic fluid may play role in the pathogenesis of DS. Defining their potential as biochemical pathogenic factors of DS requires further investigation of the biological pathways involving in the foetal development.

The Significance of Apolipoprotein E Measurement in the Screening of Fetal Down Syndrome.

Prenatal screening for Down syndrome (DS) is based on both noninvasive and invasive methods. Noninvasive, cell-free fetal DNA genetic tests are expensive, whereas biochemical methods remain imprecise. Amniocentesis is the most frequently used invasive diagnosis procedure, characterized by 99.8% diagnostic efficiency and less than 1% risk of miscarriage. The aim of this study was to evaluate the screening value of apolipoprotein E (ApoE) as a potential noninvasive biomarker for prenatal DS assessment. This study was conducted on a group of female patients who decided to undergo routine amniocentesis between the 15th and 18th week of pregnancy at the Department of Reproduction and Gynecological Endocrinology of the Medical University of Bialystok, Poland. For the purpose of this study, 20 women with DS fetuses were selected as the study group, and 20 healthy pregnant women with euploid fetus karyotypes as the control group. The plasma levels of ApoE were significantly higher in the study group compared to healthy subjects (p < 0.05). The area under the receiver operating characteristic (ROC) curve was 0.978 (p < 0.001), with the cut-off set to 1.37 mg/mL, which was characterized by 80% of sensitivity and 100% of specificity. The high sensitivity and specificity demonstrate the screening utility of maternal ApoE concentration in prenatal fetal DS screening.

Aberran sağ subklavyen arter: Down sendromu ve konjenital kalp hastalığı için güçlü bir belirteç midir?

Amac: Fetal aberran sag subklavyen arter (ARSA) ile Down sendromu arasindaki iliski uzun zamandir bilinmektedir. Calismamizin amaci populasyonumuzdaki ARSA insidansini ve Down sendromu ve konjenital kalp hastaliklari (KKH) ile iliskisini belirlemektir. Gerec ve Yontem: 2015-2018 yillari arasinda ucuncu basamak merkezde prenatal tani icin 3150 gebeye fetal ekokardiyografi yapildi. ARSA varligi, fetal ekokardiyografi sirasinda transvers 3 damar trakea planinda renkli Doppler sonografide goruntulenmesi ile dogrulandi. Calismamizda ARSA'nin sikligi ve Down sendromu ile korelasyonu arastirildi. Bulgular: 3150 hasta arasinda 42 fetuste (% 1.3) ARSA, 36 fetuste (% 1.14) izole ARSA saptandi. Down sendromlu dokuz fetusten iki hastada (% 22.2) ARSA pozitifti. ARSA, KKH olan fetuslerden sadece birinde pozitifti (% 4.1). Izole ARSA'nin Down sendromu ve CHD icin pozitif olasilik oranlari sirasiyla 0.73 ve 3.81 idi. Sonuc: Olgu serimizde, prenatal ARSA'nin saptanmasi Down sendromu icin tek basina guclu bir marker gibi gorunmemektedir ve izole ARSA, KKH ile zayif bir iliski gostermektedir.

Identification of fetal unmodified and 5-hydroxymethylated CG sites in maternal cell-free DNA for non-invasive prenatal testing

BackgroundMassively parallel sequencing of maternal cell-free DNA (cfDNA) is widely used to test fetal genetic abnormalities in non-invasive prenatal testing (NIPT). However, sequencing-based approaches are still of high cost. Building upon previous knowledge that placenta, the main source of fetal circulating DNA, is hypomethylated in comparison to maternal tissue counterparts of cfDNA, we propose that targeting either unmodified or 5-hydroxymethylated CG sites specifically enriches fetal genetic material and reduces numbers of required analytical sequencing reads thereby decreasing cost of a test.MethodsWe employed uTOPseq and hmTOP-seq approaches which combine covalent derivatization of unmodified or hydroxymethylated CG sites, respectively, with next generation sequencing, or quantitative real-time PCR.ResultsWe detected increased 5-hydroxymethylcytosine (5hmC) levels in fetal chorionic villi (CV) tissue samples as compared with peripheral blood. Using our previously developed uTOP-seq and hmTOP-seq approaches we obtained whole-genome uCG and 5hmCG maps of 10 CV tissue and 38 cfDNA samples in total. Our results indicated that, in contrast to conventional whole genome sequencing, such epigenomic analysis highly specifically enriches fetal DNA fragments from maternal cfDNA. While both our approaches yielded 100% accuracy in detecting Down syndrome in fetuses, hmTOP-seq maintained such accuracy at ultra-low sequencing depths using only one million reads. We identified 2164 and 1589 placenta-specific differentially modified and 5-hydroxymethylated regions, respectively, in chromosome 21, as well as 3490 and 2002 Down syndrome-specific differentially modified and 5-hydroxymethylated regions, respectively, that can be used as biomarkers for identification of Down syndrome or other epigenetic diseases of a fetus.ConclusionsuTOP-seq and hmTOP-seq approaches provide a cost-efficient and sensitive epigenetic analysis of fetal abnormalities in maternal cfDNA. The results demonstrated that T21 fetuses contain a perturbed epigenome and also indicated that fetal cfDNA might originate from fetal tissues other than placental chorionic villi. Robust covalent derivatization followed by targeted analysis of fetal DNA by sequencing or qPCR presents an attractive strategy that could help achieve superior sensitivity and specificity in prenatal diagnostics.

Genome-wide miRNA profiling in plasma of pregnant women with down syndrome fetuses

Down syndrome (DS) is one of the most common causes of intellectual disability and new approaches allowing its rapid and effective prenatal detection are being explored. In this study, we investigated the diagnostic potential of plasma microRNAs (miRNAs). This study builds upon our previous study in DS placentas, where seven miRNAs were found to be significantly up-regulated. A total of 70 first-trimester plasma samples from pregnant women were included in the present study (35 samples with DS fetuses; 35 with euploid fetuses). Genome-wide miRNA profiling was performed in the pilot study using Affymetrix GeneChip™ miRNA 4.1 Array Strips (18 samples). Selected miRNAs were then analysed in the validation study using quantitative reverse transcription PCR (RT-qPCR; 52 samples). Based on the current pilot study results (12 miRNAs), our previous research on chorionic villi samples (7 miRNAs) and the literature (4 miRNAs), a group of 23 miRNAs was selected for the validation study. Although the results of the pilot study were promising, the validation study using the more sensitive RT-qPCR technique and a larger group of samples revealed no significant differences in miRNA profiles between the compared groups. Our results suggest that testing of the first-trimester plasma miRNAs is probably not suitable for non-invasive prenatal testing (NIPT). Different results could be theoretically achieved at later gestational ages; however, such a result probably would have limited use in clinical practice.

Differential expression profile study and gene function analysis of maternal foetal-derived circRNA for screening for Down's syndrome.

Recent studies have shown that circular RNAs (circRNAs) exhibit differential expression in certain diseases. However, to the best of our knowledge, maternal fetal-derived circRNAs and mRNAs associated with Down's syndrome (DS) have not yet been investigated. A total of 12 umbilical cord blood samples were collected from pregnant women, including six women carrying fetuses with DS (diagnosed by G-banding karyotype analysis), and six women carrying fetuses without DS. In addition, 12 peripheral blood samples were obtained from children, including six children with DS and six children without DS. Gene chip technology was used to screen for differentially expressed circRNAs and mRNAs in the cord blood samples, and were subsequently verified by reverse transcription-quantitative polymerase chain reaction in peripheral blood from the children to identify potential biomarkers. Furthermore, circRNA/microRNA (miRNA) interactions were predicted using Arraystar miRNA target prediction software. There was a significant difference in the expression of hsa_circRNA_103127, hsa_circRNA_103112 and hsa_circRNA_104907 between cord blood obtained from the women carrying fetuses with and without DS, and between peripheral blood obtained from children with and without DS (P<0.01). As hsa_circRNA_103112 exhibited significant differences in expression between cord blood obtained from the women carrying fetuses with and without DS and between peripheral blood obtained from children with and without DS, its corresponding gene, ubiquitin specific peptidase 25, may be involved in the pathogenesis of the condition. These results suggested that hsa_circRNA_103112 may be upregulated in individuals with DS, resulting in an expression imbalance of diploid genes through interactions among circRNA, miRNA and mRNA. Therefore, the level of hsa_circRNA_103112 in the peripheral blood of a pregnant woman may serve as potential biomarker of fetal DS during non-invasive prenatal screening.

Quantitative proteomic analysis of down syndrome biomarkers in maternal serum using isobaric tags for relative and absolute quantification (iTRAQ)

Prenatal diagnosis of Down syndrome (DS) is based on calculated risk involving maternal age, biochemical and ultrasonographic markers, and, more recently, cell-free DNA (cfDNA). The present study was designed to identify Down Syndrome biomarkers in maternal serum. We quantified the changes in maternal serum protein levels between 10 non-pregnant women, 10 pregnant women with healthy fetuses, and 10 pregnant women with DS fetuses using isobaric tags for relative and absolute quantification (iTRAQ). We subsequently conducted a Gene Ontology (GO) analysis. A total of 470 proteins were identified, 11 of which had significantly different serum levels between the DS fetus group and Healthy fetuses group. Our data shows the identified proteins may be relevant to DS and constitute potential DS biomarkers.

Epigenome-wide base-resolution profiling of DNA methylation in chorionic villi of fetuses with Down syndrome by methyl-capture sequencing

BackgroundEpigenetic mechanisms provide an interface between environmental factors and the genome and are influential in various diseases. These mechanisms, including DNA methylation, influence the regulation of development, differentiation, and establishment of cellular identity. Here, we performed high-throughput methylome profiling to determine whether differential patterns of DNA methylation correlate with Down syndrome (DS).Materials and methodsWe extracted DNA from the chorionic villi cells of five normal and five DS fetuses at the early developmental stage (12–13 weeks of gestation). Methyl-capture sequencing (MC-Seq) was used to investigate the methylation levels of CpG sites distributed across the whole genome to identify differentially methylated CpG sites (DMCs) and regions (DMRs) in DS. New functional annotations of DMR genes using bioinformatics tools were predicted.ResultsDNA hypermethylation was observed in DS fetal chorionic villi cells. Significant differences were evident for 4,439 DMCs, including hypermethylation (n = 4,261) and hypomethylation (n = 178). Among them, 140 hypermethylated DMRs and only 1 hypomethylated DMR were located on 121 genes and 1 gene, respectively. One hundred twenty-two genes, including 141 DMRs, were associated with heart morphogenesis and development of the ear, thyroid gland, and nervous systems. The genes were significantly associated with DS and various diseases, including hepatopulmonary syndrome, conductive hearing loss, holoprosencephaly, heart diseases, glaucoma, and musculoskeletal abnormalities.ConclusionsThis is the first study to compare the whole-epigenome DNA methylation pattern of the chorionic villi cells from normal and DS fetuses at the early developmental-stage using MC-seq. Overall, our results indicate that the chorionic villi cells of DS fetuses are hypermethylated in all autosomes and suggested that altered DNA methylation may be a recurrent and functionally relevant downstream response to DS in human cells. This study provides basic information for future research focused on the pathophysiology of the DS and its potential effects, as well as the role DNA methylation plays in the early developmental stage of DS fetuses.

Fetal Down syndrome screening models for developing countries; Part II: Cost-benefit analysis

BackgroundTo identify the most cost-beneficial model as a national policy of screening and diagnosis of fetal Down syndrome (DS) in developing countries.MethodsCost-benefit analysis (CBA) was performed based on the effectiveness and probabilities derived from a large prospective study on MSS (maternal serum screening) among Thai population. Various models including maternal age alone, STS (second trimester screen), I-S (independent screen: first or second trimester screen depending on the time of first visit), C-S (contingent serum screen) plus STS, maternal age with NIPS (non-invasive prenatal test), STS alone with NIPS, I-S with NIPS, C-S plus STS with NIPS, and Universal NIPS were compared.ResultsI-S with NIPS as a secondary screening was most cost-beneficial (Benefit/Cost ratio 4.28). Cost-benefit is directly related to the costs of NIPS.ConclusionIn addition to simplicity and feasibility, I-S with expensive NIPS as a secondary screening is the most cost-beneficial method for low resource settings and should be included in universal healthcare coverage as a national policy. This study could be a model for developing countries or a guideline for international health organizations to help low resource countries, probably leading to a paradigm shift in prenatal diagnosis of fetal DS in the developing world.

Metabolic Infrastructure of Pregnant Women With Trisomy 21 Fetuses; Metabolomic Analysis.

We aimed to configure impaired/altered metabolomic profiles of pregnant women carrying Down syndrome (DS) fetuses. The study involved 21 and 32 pregnant women with DS and euploid fetuses, respectively, as determined by prenatal screening and diagnosis as part of an antenatal care program. Metabolomic analyses were carried out using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-qTOF-MS) methods. A total of 95 metabolites were identified. GC-MS analysis indicated that levels of 2-hydroxybutyric acid, benzoic acid, nonanoic acid, 3-hydroxybutyric acid, and 2-ketoisocaproic acid were increased in the DS group, where beta-alanine, threonic acid, oxalic acid, alpha-tocopherol, uracil, 2-piperidone, and creatinine were decreased. However, LC-qTOF-MS analysis showed that lipid-related metabolites were decreased in women carrying DS fetuses, whereas creatine, N4-phosphoagmatine, citrate, 2,5-dioxopentanoate, 2-furoate, pyruvate, and fructose levels were increased. Pathway analysis was also performed using metabolites whose levels were significantly altered (p<0.05) between the groups, and the findings indicated that the biosynthesis pathways of aminoacyl-tRNA and "valine-leucine-isoleucine", and metabolism pathways of "glycine-serine-threonine", nitrogen, "alanine-aspartate-glutamate", propanoate, glycerophospholipid, cysteine, methionine, and phenylalanine were significantly altered. Our findings indicate a special type of metabolic status/syndrome in pregnant women with Down syndrome fetuses. It could be speculated that altered metabolic status might influence both gametogenesis and embryogenesis. Down syndrome is a complex genetic disorder that is important to detect prenatally, but may also be prevented by taking necessary precautions prior to pregnancy.