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Improvements in antenatal screening for Down's syndrome.

ABSTRACT: To estimate improvements to four antenatal screening tests for Down's syndrome (first trimester Combined, second trimester Quadruple, and first and second trimester Integrated and Serum Integrated tests) based on adding ductus venosus pulsatility index (DVPI), fetal nasal bone examination (NBE) and serum placental growth factor (PlGF).Statistical analysis of data from several sources modelled using the maternal age distribution of live births in England and Wales from 2006 to 2008.Monte Carlo simulation carried out to estimate the screening performance of tests with the addition of combinations of DVPI, NBE and PlGF.At a 95% detection rate (DR), with first trimester markers measured at 11 completed weeks' gestation, the addition of DVPI, NBE and PlGF decreased the false-positive rate (FPR) of the Combined test from 16.1% to 3.0%, the addition of PlGF to the Quadruple test decreased the FPR from 15.7% to 15.3%, the addition of DVPI, NBE and PlGF to the Integrated test decreased the FPR from 4.1% to 0.6% and the addition of PlGF to the Serum Integrated test decreased the FPR from 15.1% to 11.1%. At a 90% detection rate, the reductions in the FPR were from 6.8% to 0.8%, 7.7% to 7.4%, 1.2% to 0.1% and 6.2% to 4.8%, respectively.The addition of DVPI, NBE and PlGF to the Combined and Integrated tests significantly improves screening performance, reducing the FPRs by over 80%. The Integrated test with DVPI, NBE and PlGF is significantly better than the Combined test with DVPI, NBE and PlGF.

SUBMITTER: Wald NJ

PROVIDER: S-EPMC5438079 | biostudies-other | 2013 Mar

REPOSITORIES: biostudies-other

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Improvements in antenatal screening for Down's syndrome.

Wald N J NJ Bestwick J P JP Huttly W J WJ

Journal of medical screening 20130301 1

<h4>Objectives</h4>To estimate improvements to four antenatal screening tests for Down's syndrome (first trimester Combined, second trimester Quadruple, and first and second trimester Integrated and Serum Integrated tests) based on adding ductus venosus pulsatility index (DVPI), fetal nasal bone examination (NBE) and serum placental growth factor (PlGF).<h4>Setting</h4>Statistical analysis of data from several sources modelled using the maternal age distribution of live births in England and Wal ...[more]

PMID: 23512549

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Project description:BACKGROUND:Screening for Down's syndrome forms part of routine obstetric practice. Ethical considerations relating to genetic screening form a major part of the workload of research ethics committees. This study investigated the attitudes of research ethics committee members to several conditions varying in clinical severity and prognosis, including Down's syndrome. METHODS:The members of 40 randomly chosen research ethics committees were surveyed. A simple questionnaire comprising 19 clinical scenarios based around four "clinical" conditions was designed to review conditions that were potentially embarrassing, affecting life span but not mental ability, premature death, and intellectual impairment with a risk of neonatal cardiac defects (Down's syndrome). Screening tests with different degrees of effectiveness were described and the diagnostic test descriptions ranged from having no risk to an unaffected fetus to causing spontaneous abortion of two normal fetuses for each affected fetus identified. Replies were graded on a scale of 1 to 5. RESULTS:Seventy seven replies were received from 28 different research ethics committees. Screening was supported for treatment of a life threatening condition (95% in favour) but screening for conditions of a slight increase in premature death (14% in favour) or cosmetic features (10% in favour) were considered unethical. Views were ambiguous (49% in favour) about conditions involving significant shortening of lifespan. Down's syndrome screening was considered more ethical when described as a serious condition (56% in favour) than when the clinical features were described (44% in favour). Once increased rates of spontaneous abortion on confirmatory testing were added, 79% (21% in favour) and 86% (14% in favour) stated that screening was unethical (for "serious" and "clinical features" descriptions, respectively). CONCLUSIONS:Down's syndrome screening raises ethical concerns about genetic testing in general that need to be dealt with before the introduction of any prenatal screening test.

Project description: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.

Project description:Basal forebrain cholinergic neurons play a key role in cognition. This neuronal system is highly dependent on NGF for its synaptic integrity and the phenotypic maintenance of its cell bodies. Basal forebrain cholinergic neurons progressively degenerate in Alzheimer's disease and Down's syndrome, and their atrophy contributes to the manifestation of dementia. Paradoxically, in Alzheimer's disease brains, the synthesis of NGF is not affected and there is abundance of the NGF precursor, proNGF. We have shown that this phenomenon is the result of a deficit in NGF's extracellular metabolism that compromises proNGF maturation and exacerbates its subsequent degradation. We hypothesized that a similar imbalance should be present in Down's syndrome. Using a combination of quantitative reverse transcription-polymerase chain reaction, enzyme-linked immunosorbent assay, western blotting and zymography, we investigated signs of NGF metabolic dysfunction in post-mortem brains from the temporal (n = 14), frontal (n = 34) and parietal (n = 20) cortex obtained from subjects with Down's syndrome and age-matched controls (age range 31-68 years). We further examined primary cultures of human foetal Down's syndrome cortex (17-21 gestational age weeks) and brains from Ts65Dn mice (12-22 months), a widely used animal model of Down's syndrome. We report a significant increase in proNGF levels in human and mouse Down's syndrome brains, with a concomitant reduction in the levels of plasminogen and tissue plasminogen activator messenger RNA as well as an increment in neuroserpin expression; enzymes that partake in proNGF maturation. Human Down's syndrome brains also exhibited elevated zymogenic activity of MMP9, the major NGF-degrading protease. Our results indicate a failure in NGF precursor maturation in Down's syndrome brains and a likely enhanced proteolytic degradation of NGF, changes which can compromise the trophic support of basal forebrain cholinergic neurons. The alterations in proNGF and MMP9 were also present in cultures of Down's syndrome foetal cortex; suggesting that this trophic compromise may be amenable to rescue, before frank dementia onset. Our study thus provides a novel paradigm for cholinergic neuroprotection in Alzheimer's disease and Down's syndrome.

Project description:BackgroundReliable antenatal identification of pre-eclampsia and small for gestational age is crucial to judicious allocation of monitoring resources and use of preventative treatment with the prospect of improving maternal/perinatal outcome. The purpose of this systematic review was to determine the accuracy of five serum analytes used in Down's serum screening for prediction of pre-eclampsia and/or small for gestational age.MethodsThe data sources included Medline, Embase, Cochrane library, Medion (inception to February 2007), hand searching of relevant journals, reference list checking of included articles, contact with experts. Two reviewers independently selected the articles in which the accuracy of an analyte used in Downs's serum screening before the 25th gestational week was associated with the occurrence of pre-eclampsia and/or small for gestational age without language restrictions. Two authors independently extracted data on study characteristics, quality and results.ResultsFive serum screening markers were evaluated. 44 studies, testing 169,637 pregnant women (4376 pre-eclampsia cases) and 86 studies, testing 382,005 women (20,339 fetal growth restriction cases) met the selection criteria. The results showed low predictive accuracy overall. For pre-eclampsia the best predictor was inhibin A>2.79MoM positive likelihood ratio 19.52 (8.33,45.79) and negative likelihood ratio 0.30 (0.13,0.68) (single study). For small for gestational age it was AFP>2.0MoM to predict birth weight < 10th centile with birth < 37 weeks positive likelihood ratio 27.96 (8.02,97.48) and negative likelihood ratio 0.78 (0.55,1.11) (single study). A potential clinical application using aspirin as a treatment is given as an example.There were methodological and reporting limitations in the included studies thus studies were heterogeneous giving pooled results with wide confidence intervals.ConclusionDown's serum screening analytes have low predictive accuracy for pre-eclampsia and small for gestational age. They may be a useful means of risk assessment or of use in prediction when combined with other tests.

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Improvements in antenatal screening for Down's syndrome.

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Improvements in antenatal screening for Down's syndrome.

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