Advances in prenatal screening for Down syndrome: I. general principles and second trimester testing

The effect of a vanishing twin on first- and second-trimester maternal serum markers and ultrasound screening for aneuploidy

A vanishing twin (VT) is the early demise of a twin fetus. It is estimated to occur in 20-30% of pregnancies associated with assisted reproductive technology. VT becomes increasingly prominent when assisted fertilization is used, because one or more embryos are transferred to the uterus. Maternal serum screening tests during pregnancy can screen for trisomy chromosomes 21, 18, and 13 and are divided into first- and second-trimester tests. In singleton pregnancies, the first trimester screening test is performed at 11-13 weeks and 6 days of gestation. It consists of two serum markers, pregnancy-associated plasma protein A and β-human chorionic gonadotropin (β-hCG), and measures nuchal translucency thickness. The second-trimester screening test was performed at 15-20 weeks and 6 days of gestation. It consists of four serum markers: alpha-fetoprotein, β-hCG, unconjugated estriol, and inhibin A. More effective screening for trisomy 21 in singleton pregnancies is achieved by analyzing cell-free DNA in the maternal blood. A VT includes a demise of the fetus. Although it affects maternal serum markers, it has not been corrected. Five studies examined the effect of VT on maternal serum markers, but the results were controversial. This study aimed to review the patterns of changes in maternal serum markers in VTs, interpret prenatal tests for pregnant women with VTs in clinical practice, and consider what information should be provided.

Biochemical Screening for Fetal Trisomy 21: Pathophysiology of Maternal Serum Markers and Involvement of the Placenta

It is now well established that maternal serum markers are often abnormal in fetal trisomy 21. Their determination is recommended for prenatal screening and pregnancy follow-up. However, mechanisms leading to abnormal maternal serum levels of such markers are still debated. Our objective was to help clinicians and scientists unravel the pathophysiology of these markers via a review of the main studies published in this field, both in vivo and in vitro, focusing on the six most widely used markers (hCG, its free subunit hCGβ, PAPP-A, AFP, uE3, and inhibin A) as well as cell-free feto-placental DNA. Analysis of the literature shows that mechanisms underlying each marker's regulation are multiple and not necessarily directly linked with the supernumerary chromosome 21. The crucial involvement of the placenta is also highlighted, which could be defective in one or several of its functions (turnover and apoptosis, endocrine production, and feto-maternal exchanges and transfer). These defects were neither constant nor specific for trisomy 21, and might be more or less pronounced, reflecting a high variability in placental immaturity and alteration. This explains why maternal serum markers can lack both specificity and sensitivity, and are thus restricted to screening.

Temporal Trends in New Registrations for the Ontario Cleft Lip and Palate/Craniofacial Dental Program Between 2007 and 2018

BACKGROUND

The Ontario Cleft Lip and Palate/Craniofacial Dental Program was established to fund dental care for those with oral clefts, craniofacial anomalies, congenital oral defects, and acquired facial/oral defects.

AIM

To determine the annual rates of newly registered oral clefts, craniofacial anomalies, congenital oral defects, and acquired oral defects cases on the Program from 2007 to 2018 and identify trends in registration rates during this time period.

DESIGN

Data were obtained from the Program from 2007 to 2018. Annual, age-specific incidence rates (for age groups 0-4, 5-9, 10-14, 15-19, and 20-24 years) were calculated for new registrations in each diagnostic category, plotted and examined using Poisson regression analysis to identify trends.

RESULTS

Rates of new registration for oral clefts and acquired oral defects were stable from 2007 to 2018. The rates of newly registered cases of craniofacial anomalies and congenital oral defects showed an increased trend from 2007 to 2018, although year-by-year comparison of the change in rates did not reach statistical significance. For craniofacial anomalies, congenital oral defects, and acquired oral defects, the highest rates of new registrations occurred in the age group 10 to 14 years, while those aged 0 to 4 recorded the highest registration rates in the oral cleft group.

CONCLUSION

Rates in new cleft and acquired oral defects registrations were stable from 2007 to 2018. Rates in newly registered cases of craniofacial anomalies and congenital oral defects increased over the 11-year period.

Proficiency testing of maternal serum prenatal screening in second trimester in China, 2015

Introduction

Prenatal screening and diagnosis is important for the detection of birth defects and genetic diseases. The nationwide proficiency testing (PT) of maternal serum prenatal screening in second trimester in China has been launched since 2003 and partly reflected the performance of screening laboratories. This study analysed the 2015 PT results to examine the performance of clinical laboratories and different platforms.

Materials and methods

Fifteen lyophilized samples with different concentrations divided into three panels, were distributed to 613 clinical laboratories in 2015. Acceptable performance was defined as scores more than 80% of acceptable responses with the evaluation criterion of ± 30%. The robust coefficient of variation (CV) was also analysed. Chi-square (χ2) test was used to compare the acceptable performance while Kruskal-Wallis test and Mann-Whitney test were applied to compare the robust CV among analytes and mainstream platforms.

Results

Overall, 605, 61, 214, 416, 303 laboratories submitted effective results for alpha fetoprotein (AFP), total human chorionic gonadotropin (t-hCG), β-hCG, unconjugated estriol (uE3) and free β-hCG. The acceptable performances of AFP (μg/L), AFP (KIU/L), t-hCG, β-hCG, uE3, and free β-hCG were 98.45%, 99.24%, 95.58%, 98.72%, 94.50%, and 98.66%, respectively. The χ2 test indicated significant differences existed in the acceptable performances among different analytes and platforms for uE3. Kruskal-Wallis test and Mann-Whitney test suggested the robust CV differed significantly in different analytes and platforms.

Conclusions

The majority of results were acceptable. However, further effort is needed to achieve the standardization and harmonization among analytes and various platforms, particularly for uE3.

Landmark detection from 3D mesh facial models for image-based analysis of dysmorphology

Facial landmark detection is a task of interest for facial dysmorphology, an important factor in the diagnosis of genetic conditions. In this paper, we propose a framework for feature points detection from 3D face images. The method is based on 3D Constrained Local Model (CLM) which learns both global variations in the 3D facial scan and local changes around every vertex landmark. Compared to state of the art methods our framework is distinguished by the following novel aspects: 1) It operates on facial surfaces, 2) It allows fusion of shape and color information on the mesh surface, 3) It introduces the use of LBP descriptors on the mesh. We showcase our landmarks detection framework on a set of scans including down syndrome and control cases. We also validate our method through a series of quantitative experiments conducted with the publicly available Bosphorus database.

Pathology consultation on human chorionic gonadotropin testing for pregnancy assessment

OBJECTIVES

To provide clarity on the use of qualitative and quantitative human chorionic gonadotropin (hCG) tests for the assessment of pregnancy.

METHODS

A case scenario and a brief review of the relevant literature describing clinical and analytical considerations regarding hCG testing are presented.

RESULTS

In pregnancy, hCG is nearly always detectable in serum and urine within 16 days after ovulation. Serial hCG testing is valuable in the evaluation of suspected ectopic pregnancy. hCG assays vary in their analytical specificity, and qualitative tests may be less analytically sensitive than claimed. Erroneous hCG test results can occur for several reasons.

CONCLUSIONS

hCG assays are reliable diagnostic tests for pregnancy assessment, but a clear understanding of their limitations is necessary for appropriate result interpretation.

Pregnancy associated plasma protein-A2: a novel biomarker for Down syndrome

INTRODUCTION

In an effort to improve prenatal screening for Trisomy 21, we evaluated pregnancy associated plasma protein-A2 (PAPP-A2) as a potential novel second trimester biomarker for Trisomy 21.

METHODS

Trisomy 21 and normal control mid-trimester placental samples were subjected to quantitative rt PCR analysis of seven genes we had previously found to be differentially expressed in Trisomy 21 placentae. The localization and differential expression of PAPP-A2 in second trimester placentae from normal and Trisomy 21 pregnancies was determined by immunohistochemistry. PAPP-A2 maternal serum protein levels in ten Trisomy 21 and ten diploid pregnancies were compared by Western blotting. Maternal serum PAPP-A2 levels were measured in 30 Down syndrome cases and 142 normal controls, using ELISA. Regression analysis was used to determine the correlation of PAPP-A2 with other existing markers of Trisomy 21.

RESULTS

PAPP-A2 (aka PLAC 3) mRNA and protein expression were both increased in Down syndrome placentae as compared to diploid placentae. PAPP-A2 was also increased in maternal serum from Down syndrome pregnancies as compared to diploid pregnancies. PAPP-A2 expression correlated weakly with established markers.

DISCUSSION

This work takes advantage of our previously performed systematic approach to the discovery of novel maternal serum biomarkers for Trisomy 21, using cDNA microarray analysis. Beginning with the validation of the microarray results, we have tracked PAPP-A2 overexpression in Down syndrome from placental mRNA to maternal serum protein.

CONCLUSION

PAPP-A2 could serve as an additional maternal serum marker in prenatal screening for Trisomy 21.

Triple test screening for Down syndrome: an Egyptian-tailored study

BACKGROUND

The incidence of Down syndrome (DS) in Egypt varies between 1:555 and 1:770 and its screening by triple test is becoming increasingly popular nowadays. Results, however, seem inaccurate due to the lack of Egyptian-specific information needed for risk calculation and a clear policy for programme implementation. Our study aimed at calculation and validation of the triple marker medians used in screening Egyptian females as well as to recommend programme conventions to unify screening in this country.

METHODS

The study was conducted on 668 Egyptian women, in weeks 15-20 of pregnancy as proven by sonar. Chorionic gonadotropin (CG), α-fetoprotein (AFP) and unconjugated oestriol (uE3) were measured on Siemens Immulite analyzer. Medians of the three parameters were calculated, regressed against gestational age (GA) and weighted by the number of participants/week. Equations were derived to adjust each parameter to the maternal weight and were centered on the median Egyptian weight. Prisca software was fed with the above data, multiples-of-median (MoM) and DS risks were calculated and the screening performance was evaluated at a mid-trimester risk cutoff of 1:270.

RESULTS

Log-linear [AFP/uE3 = 10(A+B*GA)] and exponential equations [CG = A*e (B*GA)] were derived and the regressed medians were found to follow similar patterns to other Asian and Western medians. Oestriol was always lowest (even halved) while CG and AFP were intermediate. A linear reciprocal model best fitted weight distribution among Egyptians and successfully adjusted each parameter to a weight of 78.2 kg. Epidemiological monitoring of these recommendations revealed satisfactory performance in terms of 6.7% initial positive rate and 1.00 grand MoM.

CONCLUSIONS

Adoption of the above recommendations is hoped to pave the way to a successful DS screening programme tailored to Egyptian peculiarities.

The role of unexplained high serum alpha-fetoprotein (AFP) and human chorionic gonadotropin (hCG) levels in the second trimester to determine poor obstetric outcomes

Objective:

To investigate the relationship between gestational complications and high levels of maternal serum alfa-fetoprotein (MSAFP) and/or beta human chorionic gonadotropin (hCG) and to determine whether these markers are effective predictors of poor pregnancy outcomes.

Materials and Methods:

In this study, we enrolled a total of 679 women at 15-20 gestational weeks with MSAFP and hCG below or above 2.0 multiples of the median (MoM); of those, 200 women with normal MSAFP and hCG MoM formed the control group. Pre-eclampsia, intrauterine growth retardation (IUGR), preterm labor, preterm delivery, placental abruption, placenta previa, placenta accreta, preterm premature rupture of the membranes (PPROM), intrauterine fetal death, as well as neonatal and perinatal morbidity rates were evaluated.

Results:

A significant relationship was found between adverse pregnancy outcomes and abnormal elevation of hCG and AFP levels in the second trimester. In cases of isolated elevation of hCG, preeclampsia and preterm labor/spontaneous preterm birth rate were slightly higher than in the control group (p=0.043, p=0.015), while IUGR, PPROM, placental abruption, and intrauterine fetal death rates were all similar (p=0.063, p=0.318, p=1.00, p=0.556).

In case having an elevation in both markers, increased rate of obstetric complications have been observed. A significant relationship was found between the high levels of maternal serum AFP and hCG MoM and poor pregnancy outcomes like preeclampsia, IUGR, PPROM, intrauterine fetal death (p=0.003, p=0.001, p=0.040, p=0.006).

Conclusion:

To our knowledge, up to now, no definitive follow-up and treatment protocols have been established for patients at increased risk. In light of these findings, it is recommended to inform and educate patients about the most likely signs and symptoms of complications, to make more often antenatal visits, to perform more frequent ultrasound examination (fetal growth, AFI, etc.), NST, arterial/venous doppler, biophysical profile, and cervical length measurements in high-risk group.

Hierarchical constrained local model using ICA and its application to Down syndrome detection

Conventional statistical shape models use Principal Component Analysis (PCA) to describe shape variations. However, such a PCA-based model assumes a Gaussian distribution of data. A model with Independent Component Analysis (ICA) does not require the Gaussian assumption and can additionally describe the local shape variation. In this paper, we propose a Hierarchical Constrained Local Model (HCLM) using ICA. The first or coarse level of HCLM locates the full landmark set, while the second level refines a relevant landmark subset. We then apply the HCLM to Down syndrome detection from photographs of young pediatric patients. Down syndrome is the most common chromosomal condition and its early detection is crucial. After locating facial anatomical landmarks using HCLM, geometric and local texture features are extracted and selected. A variety of classifiers are evaluated to identify Down syndrome from a healthy population. The best performance achieved 95.6% accuracy using support vector machine with radial basis function kernel. The results show that the ICA-based HCLM outperformed both PCA-based CLM and ICA-based CLM.

Ensemble learning for the detection of facial dysmorphology

Down syndrome is the most common chromosomal condition that presents characteristic facial morphology and texture patterns. The early detection of Down syndrome through an automatic, non-invasive and simple way is desirable and critical to provide the best health management to newborns. In this study, we propose such a computer-aided diagnosis system for Down syndrome from photography based on facial analysis with ensemble learning. First, geometric and texture facial features are extracted based on automatically located facial landmarks, followed by feature fusion and selection. Then multiple classifiers (i.e. support vector machines, random forests and linear discriminant analysis) are adopted to identify patients with Down syndrome. An accurate and reliable decision is finally achieved by optimally combining the outputs of these individual classifiers via ensemble learning that captures both the shared and complementary information from different classifiers. The best performance was achieved by using the median ensemble rule with 0.967 accuracy, 0.977 precision and 0.933 recall.

Early pregnancy diagnosis in bovines: current status and future directions

An early and accurate diagnosis of reproductive dysfunctions or aberrations is crucial to better reproductive management in livestock. High reproductive efficiency is a prerequisite for high life-time production in dairy animals. Early pregnancy diagnosis is key to shorten the calving interval through early identification of open animals and their timely treatment and rebreeding so as to maintain a postpartum barren interval close to 60 days. A buffalo, the most important dairy animal in the Indian subcontinent, is known for problems related to high calving interval, late puberty, and high incidence of anestrus. Lack of reliable cow-side early pregnancy diagnosis methods further aggravates the situation. Several methods of pregnancy diagnosis are being practiced in bovine species, yet none qualifies as the ideal pregnancy diagnosis method due to the inherent limitations of sensitivity, accuracy, specificity, speed, and ease of performing the test. The advancement of molecular techniques like proteomics and their applications in animal research has given a new hope to look for pregnancy biomarker molecules in these animals. This review attempts to examine common pregnancy diagnosis methods available for dairy animals, while assessing the usefulness of the modern technologies in detecting novel pregnancy markers and designing future strategies for research in this area.

Non-genomic effects of xenoestrogen mixtures

Xenoestrogens (XEs) are chemicals derived from a variety of natural and anthropogenic sources that can interfere with endogenous estrogens by either mimicking or blocking their responses via non-genomic and/or genomic signaling mechanisms. Disruption of estrogens' actions through the less-studied non-genomic pathway can alter such functional end points as cell proliferation, peptide hormone release, catecholamine transport, and apoptosis, among others. Studies of potentially adverse effects due to mixtures and to low doses of endocrine-disrupting chemicals have recently become more feasible, though few so far have included actions via the non-genomic pathway. Physiologic estrogens and XEs evoke non-monotonic dose responses, with different compounds having different patterns of actions dependent on concentration and time, making mixture assessments all the more challenging. In order to understand the spectrum of toxicities and their mechanisms, future work should focus on carefully studying individual and mixture components across a range of concentrations and cellular pathways in a variety of tissue types.

Birth weight, breast cancer and the potential mediating hormonal environment

Background

Previous studies have shown that woman’s risk of breast cancer in later life is associated with her infants birth weights. The objective of this study was to determine if this association is independent of breast cancer risk factors, mother’s own birth weight and to evaluate association between infants birth weight and hormonal environment during pregnancy. Independent association would have implications for understanding the mechanism, but also for prediction and prevention of breast cancer.

Methods and Findings

Risk of breast cancer in relation to a first infant’s birth weight, mother’s own birth weight and breast cancer risk factors were evaluated in a prospective cohort of 410 women in the Framingham Study. Serum concentrations of estriol (E3), anti-estrogen alpha-fetoprotein (AFP), and pregnancy-associated plasma protein-A (PAPP-A) were measured in 23,824 pregnant women from a separate prospective cohort, the FASTER trial. During follow-up (median, 14 years) 31 women (7.6 %) were diagnosed with breast cancer. Women with large birth weight infants (in the top quintile) had a higher breast cancer risk compared to other women (hazard ratio (HR), 2.5; 95% confidence interval (CI), 1.2–5.2; P = 0.012). The finding was not affected by adjustment for birth weight of the mother and traditional breast cancer risk factors (adjusted HR, 2.5; 95% CI, 1.2–5.6; P = 0.021). An infant’s birth weight had a strong positive relationship with the mother’s serum E3/AFP ratio and PAPP-A concentration during pregnancy. Adjustment for breast cancer risk factors did not have a material effect on these relationships.

Conclusions

Giving birth to an infant with high birth weight was associated with increased breast cancer risk in later life, independently of mother’s own birth weight and breast cancer risk factors and was also associated with a hormonal environment during pregnancy favoring future breast cancer development and progression.

Endocrine disruption via estrogen receptors that participate in nongenomic signaling pathways

When inappropriate (non-physiologic) estrogens affect organisms at critical times of estrogen sensitivity, disruption of normal endocrine functions can result. Non-physiologic estrogen mimetics (environmental, dietary, and pharmaceutical) can signal rapidly and potently via the membrane versions of estrogen receptors, as can physiologic estrogens. Both physiologic and non-physiologic estrogens activate multiple signaling pathways, leading to altered cellular functions (e.g. peptide release, cell proliferation or death, transport). Xenoestrogens' mimicry of physiologic estrogens is imperfect. When superimposed, xenoestrogens can alter endogenous estrogens' signaling and thereby disrupt normal signaling pathways, leading to malfunctions in many tissue types. Though these xenoestrogen actions occur rapidly via nongenomic signaling pathways, they can be sustained with continuing ligand stimulation, combinations of ligands, and signaling that perpetuates downstream, eventually also impinging on genomic regulation by controlling the activation state of transcription factors. Because via these pathways estrogens and xenoestrogens cause nonmonotonic stimulation patterns, they must be carefully tested for activity and toxicity over wide dose ranges. Nongenomic actions of xenoestrogens in combination with each other, and with physiologic estrogens, are still largely unexplored from these mechanistic perspectives.

Options for Down Syndrome Screening: What Will Women Choose?

Down syndrome screening has been offered to pregnant women since the early 1980s. Protocols have changed as research confirmed improvements that result in higher detection rates and lower false-positive rates. Results from 2 clinical trials evaluating screening protocols that include ultrasound measurement of nuchal translucency and biochemical testing in the first and second trimester are now available. First-trimester screening is an option if there are adequate ultrasound, diagnostic, and counseling services available. Regional variation in the availability of these services may limit the implementation of first-trimester screening. Combining screening tests for Down syndrome from both trimesters as an integrated test offers the highest detection rate with the lowest false-positive rate. The possibility of avoiding a positive screen will make this an attractive option for some. Timing, detection rate, false-positive rates, and personal factors influence the decision women make regarding screening versus diagnostic testing. This article reviews the efficacy of current protocols for Down syndrome screening. Accurate information about available screening tests will facilitate informed decisions about screening and testing.

Prenatal screening for chromosome abnormalities in a region with no access to termination of pregnancy

OBJECTIVE

To analyze the different variables that affect couples' decision-making about prenatal screening of chromosome abnormalities in a population with limited access to prenatal diagnosis and no legal termination of pregnancy (TOP).

METHODS

From February through August 2004, 79 couples who requested for prenatal screening at centers from Argentina and Uruguay participated in a study. A cross-sectional survey was administered to assess attitudes toward prenatal screening, the decision-making process, and knowledge and attitudes toward TOP.

RESULTS

Mean maternal age was 32.8 +/- 0.4 years. Among the couples, 88.61% knew that TOP due to fetal anomalies is not legal in their countries. When asked about the possibility of TOP in case of a serious fetal anomaly, 53% would contemplate this option.

CONCLUSION

Prenatal screening is a common practice worldwide. However, unlike most developed countries, our region has a limited access to prenatal diagnosis and no legal TOP. Those couples who stated that 'reassurance about fetal well-being' was the most important reason to perform prenatal screening had more positive attitudes toward TOP than those who considered this screening important 'to be better prepared to receive the baby'. Our findings can be used to inform and revise current health-care policies.

The prevalence of live birth Down syndrome in the region of Primorsko-goranska County in Croatia, 1996-2005: the impact of screening and amniocentesis

OBJECTIVES

To investigate the prevalence of live birth Down syndrome (DS) in the region of Primorsko-goranska County (PGC) in Croatia from 1996 to 2005 and to evaluate the impact of second-trimester maternal serum screening (MSS) and amniocentesis on live birth DS prevalence.

METHODS

Study was based on databases from the Department of Gynecology and Obstetrics, University Hospital Centre Rijeka, the Department of Biology and Medical Genetics, School of Medicine, University of Rijeka, and the Croatian National Institute of Public Health. The regional policy of prenatal diagnosis for DS includes amniocentesis for pregnant women aged 35 or over and MSS for younger women. We estimated live birth and total prevalence of DS and measured the proportion of pregnant women using MSS and amniocentesis. Trends of live birth and total prevalence of DS were tested by linear regression analysis.

RESULTS

The live birth prevalence of DS was 1.4/1000 in the period 1996-2005. A decreasing, but nonsignificant, trend of prevalence was observed over time (P = 0.577). Women aged 35 or over represented 11.6% of all pregnant women included in the study. The proportion of women who had MSS was 33.9%. The proportion who underwent amniocentesis was 6.1%.

CONCLUSIONS

No marked decrease in prevalence of live birth DS was observed in the region of PGC during the last 10 years. The usage of MSS and amniocentesis was too low to have any significant impact on live birth DS prevalence. Women's, as well as physician's, knowledge and attitudes towards prenatal diagnosis of DS should be evaluated.

ADAM 12 as a second-trimester maternal serum marker in screening for Down syndrome

BACKGROUND

ADAM 12 is a placenta-derived glycoprotein that is involved in growth and differentiation. The maternal serum concentration of ADAM 12 is a potential first-trimester maternal serum marker of Down syndrome (DS). Here we examine the potential of ADAM 12 as a second-trimester maternal serum marker of DS.

MATERIALS AND METHODS

The concentration of ADAM 12 was determined in gestational week 14-19 in 88 DS pregnancies and 341 matched control pregnancies. Medians of normal pregnancies were established by polynomial regression and the distribution of log(10) MoM ADAM 12 values in DS pregnancies and controls determined. Correlations with alpha-fetoprotein (AFP) and free beta-human chorionic gonadotrophin (free beta-hCG) were established and used to model the performance of maternal serum screening with ADAM 12 in combination with other second-trimester serum markers.

RESULTS

The ADAM 12 maternal serum concentration was significantly increased with a median MoM of 1.85 and a mean log(10) MoM (SD) of 0.268 (0.2678) compared to a mean log(10) MoM (SD) of 0.013 (0.4318) in controls. ADAM 12 correlated with maternal weight and ethnicity (with the serum concentration increased in Afro-Caribbeans), but neither with maternal age nor gestational age, and only marginally with AFP (r(DS) = 0.078, r(controls) = 0.093) and free beta-hCG (r(DS) = 0.073, r(controls) = 0.144. The increase in detection rate-for a false positive rate of 5%--by adding ADAM 12 to the double test (AFP + free beta-hCG) was 4%, similar to that of adding uE3 to the double test.

CONCLUSION

ADAM 12 is an efficient second-trimester marker for DS. Further studies should be conducted to determine whether it may be a useful additional or alternative marker to those currently used in the second-trimester.

Reproducibility of Risk Figures in 2nd-Trimester Maternal Serum Screening for Down Syndrome: Comparison of 2 Laboratories

Background: Analytical error affects 2nd-trimester maternal serum screening for Down syndrome risk estimation. We analyzed the between-laboratory reproducibility of risk estimates from 2 laboratories.

Methods: Laboratory 1 used Bayer ACS180 immunoassays for α-fetoprotein (AFP) and human chorionic gonadotropin (hCG), Diagnostic Systems Laboratories (DSL) RIA for unconjugated estriol (uE3), and DSL enzyme immunoassay for inhibin-A (INH-A). Laboratory 2 used Beckman immunoassays for AFP, hCG, and uE3, and DSL enzyme immunoassay for INH-A. Analyte medians were separately established for each laboratory. We used the same computational algorithm for all risk calculations, and we used Monte Carlo methods for computer modeling.

Results: For 462 samples tested, risk figures from the 2 laboratories differed >2-fold for 44.7%, >5-fold for 7.1%, and >10-fold for 1.7%. Between-laboratory differences in analytes were greatest for uE3 and INH-A. The screen-positive rates were 9.3% for laboratory 1 and 11.5% for laboratory 2, with a significant difference in the patients identified as screen-positive vs screen-negative (McNemar test, P <0.001). Computer modeling confirmed the large between-laboratory risk differences.

Conclusion: Differences in performance of assays and laboratory procedures can have a large effect on patient-specific risks. Screening laboratories should minimize test imprecision and ensure that each assay performs in a manner similar to that assumed in the risk computational algorithm.

Informed decision making in the context of prenatal screening

OBJECTIVE

This study aimed to construct a measure of informed decision making that includes knowledge, deliberation, and value-consistency, and to assess the level of informed decision making about prenatal screening, and differences between test acceptors and test decliners.

METHODS

Women attending one of 44 midwifery and gynaecology practices were asked to fill out postal questionnaires before and after the prenatal screening offer. The principal outcome was the level of informed decision making. For this purpose, knowledge about prenatal screening, deliberation about the pros and cons of the alternatives, test uptake, and attitude towards having a prenatal screening test were measured.

RESULTS

Eighty-four percent of the participants were sufficiently knowledgeable about prenatal screening, 75% of the decisions were deliberate, and 82% were value-consistent. Fifty-one percent of the participants made an informed decision. Test acceptors made less informed decisions as compared to test decliners. This difference was mainly caused by the lower rate of deliberation in this group.

CONCLUSION

It appears from this study that prenatal screening decisions are often not informed decisions. This is inconsistent with the main objective of offering screening, which is to enable people to make informed decisions.

PRACTICE IMPLICATIONS

Decision makers should be encouraged during the counselling to deliberate about the various alternatives.

Diagnostic challenges for multiplexed protein microarrays

Multiplexed protein analysis using planar microarrays or microbeads is growing in popularity for simultaneous assays of antibodies, cytokines, allergens, drugs and hormones. However, this new assay format presents several new operational issues for the clinical laboratory, such as the quality control of protein-microarray-based assays, the release of unrequested test data and the use of diagnostic algorithms to transform microarray data into diagnostic results.

A resistive-pulse sensor chip for multianalyte immunoassays

MultiAnalyte immunoassays are often required to diagnose a pathologic condition. Here, we show how resistive-pulse sensing and multiple artificial pores can be integrated together on a single chip to detect different antigens rapidly and simultaneously. We use multiple pores on a single chip to detect the size change of latex colloids upon specific antigen-antibody binding on the colloid surface. As a proof-of-principle, we demonstrate our ability to detect simultaneously human G-CSF and GM-CSF antigens on a single chip. Our novel technique is a scalable technology that can lead to the sensing of at least N2 antigens simultaneously with an N N array of pores on a single chip.

Are pregnant women making informed choices about prenatal screening?

PURPOSE

Prenatal screening should enable pregnant women to make informed choices. An informed decision is defined as being based on sufficient, relevant information and consistent with the decision maker's values. This study aims to assess to what extent pregnant women make informed choices about prenatal screening, and to assess the psychological effects of informed decision-making.

METHODS

The study sample consisted of 1159 pregnant women who were offered the nuchal translucency measurement or the maternal serum screening test. Level of knowledge, value consistency, informed choice, decisional conflict, satisfaction with decision, and anxiety were measured using questionnaires.

RESULTS

Of the participants, 83% were classified as having sufficient knowledge about prenatal screening, 82% made a value-consistent decision to accept or decline prenatal screening, and 68% made an informed decision. Informed choice was associated with more satisfaction with the decision, less decisional conflict (this applied only to test acceptors), but was not associated with less anxiety.

CONCLUSION

Although the rate of informed choice is relatively high, substantial percentages of women making uninformed choices due to insufficient knowledge, value inconsistency, or both, were found. Informed choice appeared to be psychologically beneficial. The present study underlines the importance of achieving informed choice in the context of prenatal screening.

Trends in the use of second trimester maternal serum screening from 1991 to 2003

PURPOSE

To identify trends in the utilization of second trimester maternal serum screening, follow-up amniocenteses, and the detection of Down syndrome-affected pregnancies between 1991 and 2003.

METHODS

We reviewed all triple and quadruple maternal serum screening tests referred to the University of Connecticut screening laboratory from women with singleton pregnancies. For each calendar year, the total number of tests, proportion to women aged 35 or older, number of follow-up amniocenteses, and the number of prenatally and postnatally diagnosed Down syndrome cases were recorded.

RESULTS

A total of 109,469 women received screening. In 1991, the proportion of older women who received screening was 58% of that present in the Connecticut population but by 2003 this had increased to 83% (P < 0.001). In Down syndrome screen-positive pregnancies, there was no significant change in the rate of amniocentesis utilization (average 73%), but in false-positives, there was a decline from 70% in 1991 to 27% in 2003 (P < 0.001).

CONCLUSION

Increased use of maternal serum screening by older women, use of second trimester ultrasound, and improvements in screening methodology have resulted in sharply reduced numbers of amniocenteses in unaffected pregnancies.

Accepting or declining the offer of prenatal screening for congenital defects: test uptake and women's reasons

OBJECTIVES

Prenatal screening for Down syndrome has become standard practice in many western countries. In the Netherlands, however, prenatal screening tests for congenital defects are not offered routinely. The present study aims to assess test uptake in a large, unselected population of pregnant women, and to give more insight into the decision for or against prenatal screening through nuchal translucency measurement or maternal serum screening.

PATIENTS AND METHODS

The study is part of a randomized controlled trial with two groups, each being offered a different prenatal screening test, and a control group. Pregnant women received postal questionnaires at three stages of their pregnancy.

RESULTS

Of the women being offered the nuchal translucency measurement or the second trimester maternal serum test, 53 and 38% respectively accepted the test offer. The main reasons for accepting were 'gaining knowledge about the health of the foetus/curiosity' (50%), 'favourable characteristics of the screening test' (18%), and 'increased risk of having a child with DS' (15%). The main reasons for declining were 'unfavourable characteristics of the screening test' (42%), 'not applicable/not necessary' (35%), 'anxiety/uncertainty' (36%), 'adverse characteristics of the invasive tests' (32%), and 'being against abortion' (15%).

DISCUSSION

The uptake of prenatal screening was relatively low, and different distributions of reasons were reported, compared to other studies. These differences may be due to the specific Dutch situation in which prenatal screening is not part of standard prenatal care. The question arises as to whether informed decision-making would be reduced if prenatal screening became routinised.

Epidemiology of leukemia in children with Down syndrome

Studies suggest nearly a 20-fold increased risk of leukemia in individuals with Down syndrome. Most of this increased risk appears in the first few decades of life, with the highest incidence in children less than 5 years of age. It is unknown why children with Down syndrome are at such an increased risk of leukemia. With respect to environmental exposures, it will be important to investigate risk factors associated with childhood leukemia in general (including diagnostic x-rays, pesticides, and other occupational exposures) as well as experiences common to children with Down syndrome (including routine medical screening tests, increased susceptibility to infections, and increased vitamin deficiencies).

First- and midtrimester Down syndrome screening and detection

Overall, Down syndrome detection capabilities have improved remarkably over the last 2 decades. Widely practiced first-trimester screening and less extensively elevated midtrimester urine screening promise even greater accuracy than was available a decade ago. Recently, the combination of first- and second-trimester screening has been reported to enhance discrimination of the Down syndrome fetus from normal cases. Although the advances are welcome, they present the significant prospect of multiple competitive algorithms with the risk of confusing patients, practitioners, and health care planners. The need for reasonable consensus has never been more pressing.

Biochemical screening for congenital defects

This article discusses biochemical screening for congenital defects. Biochemical screening remains the standard for estimating the risk of aneuploidy in pregnancy. The combination of first and second trimester markers promises to further improve diagnostic accuracy for anomaly detection.

Prenatal screening and diagnosis for pediatricians

The pediatrician who cares for a child with a birth defect or genetic disorder may be in the best position to alert the family to the possibility of a recurrence of the same or similar problems in future offspring. The family may wish to know about and may benefit from methods that convert probability statements about recurrence risks into more precise knowledge about a specific abnormality in the fetus. The pediatrician also may be called on to discuss abnormal prenatal test results as a way of understanding the risks and complications that the newborn infant may face. Along with the increase in knowledge brought about by the sequencing of the human genome, there has been an increase in the technical capabilities for diagnosing many chromosome abnormalities, genetic disorders, and isolated birth defects in the prenatal period. The purpose of this report is to update the pediatrician about indications for prenatal diagnosis, current techniques used for prenatal diagnosis, and the status of maternal screenings for detection of fetal abnormalities.

Down syndrome births in the United States from 1989 to 2001

OBJECTIVE

We investigated the observed and expected Down syndrome livebirths in the US from 1989 to 2001.

STUDY DESIGN

Using birth certificate data, we recorded maternal age-specific live births from 1989 to 2001, and stratified them by women 15 to 34 and 35 to 49 years old. We estimated Down syndrome live births from 1989 to 2001, assuming no terminations. We recorded Down syndrome live births by year from 1989 to 2001.

RESULTS

Despite an expected 1.32-fold increase in Down syndrome live birth rates from 1989 to 2001, Down syndrome live births actually declined. In 1989, the rate of Down syndrome cases was 15% lower than expected, decreasing to 51% by 1998. Women 15 to 34 had 45% fewer affected pregnancies in 2001, while women 35 to 49 had 53% fewer in 2001. We estimated that Down syndrome live births decreased from 3962 in 1989 to 3654 in 2001.

CONCLUSION

Down syndrome live births declined in the US despite an expected increase caused by delayed or extended childbearing.

What's new in prenatal screening and diagnosis?

This article provides clinicians with an overview of current methods for prenatal genetic screening and diagnosis. Topics include developments in prenatal screening procedures such as ethnicity-based carrier testing, maternal serum screening, and ultrasonography. Diagnostic alternatives to amniocentesis include chorionic villus sampling and preimplantation diagnosis. Future endeavors such as three-dimensional ultrasonography and fetal cell sorting are discussed.

Changes in the Utilization of Prenatal Diagnosis

OBJECTIVE

The impact of prenatal screening for Down syndrome has largely been assessed under the assumption that screening protocols and policies are fully used. To measure the overall effectiveness in actual clinical practice, we analyzed the tests performed by a single cytogenetics laboratory.

METHODS

We reviewed all amniotic fluid and chorionic villus samples (CVS) processed by the University of Connecticut Health Center's cytogenetics laboratory for the years 1991 to 2002. We evaluated trends in the use of prenatal testing, referral indications, and the numbers of cytogenetic abnormalities identified.

RESULTS

The number of women receiving amniocentesis or CVS declined more than 50% from 1,988 in 1991 to 933 in 2002 (P <.001), despite an increase in the number of women of advanced maternal age in the population served. There was a 68% decline in the number of women who underwent invasive prenatal testing solely on the basis of their age (1,314 in 1991 to 423 in 2002, P <.001). The number of Down syndrome fetuses detected prenatally increased from 20 to 31 (P =.08), representing approximately one half of the affected pregnancies present in the population served. Between 1991 and 2002, the proportion of antenatal cytogenetic tests with a significant chromosomal abnormality increased from 1 in 43 (2.3%) to 1 in 14 (7.0%; P <.001).

CONCLUSION

Advances in maternal serum screening and second-trimester ultrasonography have resulted in more judicious use of amniocentesis and chorionic villus sampling.

LEVEL OF EVIDENCE

II-2

Learning disability

Learning disability is common, affecting 1-2.5% of the general population in the Western world, and encompasses many different conditions. It usually leads to major functional impairment and lifelong need for support and interventions, not the least important of which are medical and health-care services. Rapid progress is being made in the understanding of the cause and pathogenesis of many learning disability syndromes, and these advances are likely to improve targeted interventions in the next decade. Many countries have abolished a learning disability specialty for medical professionals, but there is a great need to revive this niche of medical knowledge. We know little about quality of life and effects on families of people with learning disability, and research is needed to address these issues.

Quantitative trace analysis of estriol in human plasma by negative ion chemical ionization gas chromatography-mass spectrometry using a deuterated internal standard

A stable isotope dilution gas chromatography-mass spectrometry (GC-MS) assay for the trace level determination of estriol in human plasma is described. Negative ion chemical ionization (NICI) MS is used for highly specific detection. The method involves derivatization of the phenolic hydroxyl to the pentafluorobenzyl ether derivative and subsequent reaction of the remaining hydroxyls with heptafluorobutyric anhydride. This derivative allows detection of the strikingly abundant phenolate ion under NICI conditions. [2,4,17beta]-2H(3)-labeled estriol was used as an internal standard. For high-level measurements (>313 ng/l) plasma was directly derivatized by extractive alkylation followed by heptafluorobutylation prior to analysis. A rapid and simple sample work up procedure was elaborated for trace level determinations (>5 ng/l plasma) using solid-phase extraction on C(18) with an absolute recovery of 92.9%. For low-level measurements, the calibration curve was linear in the range of 5 to 625 ng/l (r=0.99993). Inter-assay analytical precisions (RSDs) were 1.29, 2.30 and 2.89% at 39, 156 and 650 ng/l plasma, respectively. For high-level measurements, calibration curve linearity was observed in the range of 0.313 to 20 microg/l (r=0.99998). Inter-assay analytical precisions (RSDs) were 5.17, 1.92, 2.57 and 2.74% at 0.313, 0.625, 2.5 and 10 microg/l plasma, respectively. Postmenopausal plasma was used for spiked plasma samples. Sensitivity and specificity of the presented method allows adequate determination of estriol in human plasma samples.

Management of fetal endocrine disorders

A number of maternal endocrine disorders, when active during pregnancy, can have adverse effects on the newborn. Frequently, these affects can be anticipated as in Graves' disease, or the adverse effect can be prevented as in macrosomia in the infant of the diabetic mother. Occasionally, there are opportunities for prenatal treatment of a fetal endocrine disorder. For instance, a large goitre that may cause problems during delivery can be treated with thyroid hormones administered intra-amniotically or as analogues that cross the placenta. A uniquely effective form of treatment for prevention of a major birth defect is administration of dexamethasone to the mother to avoid virilisation of a female fetus with congenital adrenal hyperplasia (CAH). However, such treatment should only be conducted within the framework of a clinical trial as the long-term effects of exposure to potent glucocorticoids in utero are unknown. Intrauterine growth retardation, which affects about 5% of newborns, is currently not amenable to direct pharmacological treatment before birth. However, there are more practical options for managing this condition, including improved maternal nutrition and avoidance of toxins injurious to fetal growth.

Landmarks in genetics through philately: Down syndrome

Down syndrome (DS) is one of the most common chromosomal disorders; however, the molecular pathogenesis and cause remains elusive. Many advances have been made in pre-natal screening and detection, but there have been few real advances in the primary prevention or treatment of DS. DS individuals have been depicted on several philatelic materials; we present some of these stamps and philatelic covers, as well as other complementary stamps, as a means to illustrate issues relevant to this disorder.