[Is Neuron-Vascular Communication Disturbed in the Delayed Prenatal Brain Development of a Mouse Model of Down Syndrome?]

Developmental retardation of the brain with reduced cortical neurogenesis is observed in Ts1Cje mice, a model of Down syndrome (DS) as it is in people with DS; however, the mechanisms and the responsible gene(s) remain unknown. The goal of the present study is to establish a therapeutic approach for treating the delayed brain development in DS. To achieve this, we have utilized multiple OMICS analyses, including proteomics and transcriptomics, to uncover the molecular alterations in the brains of DS model mice. Furthermore, we have elucidated that a transcriptional factor, the Erg gene, which is coded in the trisomic region, contributed to reduced cortical neurogenesis in the embryo of a DS mouse model by a molecular genetic technique, the "in vivo gene subtraction method". In the current review, I will introduce our recent work, the identification of the gene responsible for delayed brain development in the DS mouse model and will discuss the possibility that blood vessel dysfunction may be associated with reduced embryonic neurogenesis in DS.

Sleep quality and obstructive sleep apnoea and triple screen test results in pregnancy.

In this study, we aimed to examine the relationship between sleep quality, sleep apnoea and triple screen test results. This was an observational descriptive research study. The STOP questionnaire and the STOP-BANG questionnaire were performed to assess obstructive sleep apnoea risk and Pittsburgh Sleep Quality Index was used to evaluate sleep quality. The average Pittsburgh Sleep Quality Index score of the participants was 5.92 ± 3.26. According to the STOP test, 11.40% (87) of the pregnant women had a high risk of OSAS, and, according to the STOP-BANG test, 32 participants were under high risk of OSAS. An increased risk was detected in 1.30% of the participants in terms of Trisomy18 and in 1.60% in terms of neural tube defects. A direct and significant relationship was detected between Trisomy 21 risk and STOP-BANG score. This is the first study to show this relationship. Sufficient evidence needs to be collected on this issue. Testing in earlier weeks of pregnancy and in the conception period may allow more meaningful assessment of the relationship of OSAS with chromosomal abnormalities.IMPACT STATEMENTWhat is already known on this subject? There is a link between OSAS and epigenetic changes. Components of the triple screen test, levels of serum total ß-hCG and unconjugated oestriol are increased in OSAS.What do the results of this study add? An increase in Trisomy 21 risk is correlated with increased OSAS risk. Alpha Fetoprotein levels were higher in the low OSAS risk group.What are the implications of these findings for clinical practice and/or further research? This is the first study to show this relationship. Sufficient evidence needs to be collected on this issue. Treatment of OSAS may be necessary during pregnancy.

Mutation accumulation and developmental lineages in normal and Down syndrome human fetal haematopoiesis.

Children show a higher incidence of leukemia compared to young adolescents, yet their cells have less age-related (oncogenic) somatic mutations. Newborns with Down syndrome have an even higher risk of developing leukemia, which is thought to be driven by mutations that accumulate during fetal development. To characterize mutation accumulation in individual stem and progenitor cells of Down syndrome and karyotypically normal fetuses, we clonally expanded single cells and performed whole-genome sequencing. We found a higher mutation rate in haematopoietic stem and progenitor cells during fetal development compared to the post-infant rate. In fetal trisomy 21 cells the number of somatic mutations is even further increased, which was already apparent during the first cell divisions of embryogenesis before gastrulation. The number and types of mutations in fetal trisomy 21 haematopoietic stem and progenitor cells were similar to those in Down syndrome-associated myeloid preleukemia and could be attributed to mutational processes that were active during normal fetal haematopoiesis. Finally, we found that the contribution of early embryonic cells to human fetal tissues can vary considerably between individuals. The increased mutation rates found in this study, may contribute to the increased risk of leukemia early during life and the higher incidence of leukemia in Down syndrome.

Second Trimester Serum Biomarker Screen for Fetal Aneuploidies as a Predictor of Preterm Delivery: A Population-Based Study.

OBJECTIVE: To determine the association between second-trimester serum Down syndrome screening (alpha-fetoprotein [AFP] free beta-human chorionic gonadotropin [b-hCG] unconjugated estriol [uE3]) and preterm birth and to create predictive models for preterm birth. METHODS: Secondary analysis on a prospective database of pregnancies undergoing second-trimester screen with complete follow-up. The multiples of medians (MoM) of the biomarkers were compared between the group of term, preterm (< 37 weeks), early preterm (< 34 weeks), and very early preterm (< 32 weeks) delivery. Predictive models were developed based on adjusted MoMs and logistic regression and diagnostic performances in predicting preterm birth were determined. RESULTS: Of 20,780 pregnancies, 1,554 (7.5), 363 (1.7), and 158 (0.8%) had preterm, early preterm, and very early preterm birth respectively. High levels of AFP and b-hCG but low levels of uE3 were significantly associated with higher rates of preterm, early preterm and very early preterm delivery. The predictive models had diagnostic performance in predicting preterm birth with the areas under the ROC curve of 0.688, 0.534, 0.599, and 0.718 for AFP, b-hCG, uE3, and combined biomarkers respectively. CONCLUSION: The second trimester Down syndrome screening could also be used as a tool of risk identification of preterm birth in the same test, without extra-effort and extra-cost.

[Localization of gestational age reference table and its application in prenatal screening].

Objective: To establish a fetal biparietal diameter (BPD)-gestational age formula based on the data of pregnant women from Xiaoshan District of Hangzhou, and to evaluate its application in prenatal screening. Methods: Data of 3500 pregnant women with gestational age between 15 weeks and 19 weeks+6 receiving prenatal screening in Xiaoshan Hospital during May 2014 and May 2015 were collected. BPDs were used to establish a localized BPD-gestational age formula. The localized formula was used to evaluate the prenatal screening risks in 1759 pregnant women with irregular menstrual cycles or uncertain last menstrual period (LMP) in Xiaoshan District, and the results were compared with those calculated using formula in LifeCycle 4.0. Results: With localized formula, the total positive rate of Down syndrome, trisomy 18 syndrome and deformity of neural tube was decreased from 6.96% to 5.85% ( P<0.05), in which the positive rate of Down syndrome decreased ( P<0.05), that of deformity of neural tube increased ( P<0.05), and that of trisomy 18 syndrome remained the same ( P>0.05). The median MoMs of free-hCG ß and α-fetoprotein calculated using localized formula were significantly different from those calculated using the formula in LifeCycle 4.0 (all P<0.05), and the former ones were more closer to 1. For women of fetus diagnosed with the above diseases, the positive rate calculated using localized formula was almost the same as that calculated using the formula in LifeCycle 4.0. Conclusion: BPD-gestational age formula should be localized based on the statistical analysis of the local population, which will help to reduce the false positive rate, and make the results more accurate and reliable in prenatal screening.

Morphologic and GATA1 sequencing analysis of hematopoiesis in fetuses with trisomy 21.

Trisomy 21 alters fetal liver hematopoiesis and, in combination with somatic globin transcription factor 1 (GATA1) mutations, leads to development of transient myeloproliferative disease in newborns. However, little is known about the morphological hematopoietic changes caused by trisomy 21 in the fetus, and to date, the exact onset of GATA1 mutations remains uncertain. Therefore, we analyzed fetal liver hematopoiesis from second trimester pregnancies in trisomy 21 and screened for GATA1 mutations. We examined 57 formalin-fixed and paraffin-embedded fetal liver specimens (49 harboring trisomy 21 and 8 controls) by immunohistochemistry for CD34, CD61, factor VIII, and glycophorin A. GATA1 exon 2 was sequenced in fetal livers and corresponding nonhematologic tissue. Cell counts of megakaryocytes (P = .022), megakaryocytic precursors (P = .021), and erythroid precursors were higher in trisomy 21 cases. CD34-positive hematopoietic blasts showed no statistically significant differences. No mutation was detected by GATA1 exon 2 sequencing in fetal livers from 12 to 25 weeks of gestation. Our results suggest that GATA1 exon 2 mutations occur late in trisomy 21 fetal hematopoiesis. However, trisomy 21 alone provides a proliferative stimulus of fetal megakaryopoiesis and erythropoiesis. CD34-positive precursor cells are not increased in trisomy 21 fetal livers.

Detection of chromosomal aneuploidy in human preimplantation embryos by next-generation sequencing.

Embryos produced by assisted reproductive technologies are commonly associated with a high level of aneuploidy. Currently, 24-chromosome profiling of embryo biopsy samples by array-based methods is available to identify euploid embryos for transfer that have a higher potential for implantation and development to term. From a laboratory and patient perspective, there is a need to explore the feasibility of developing an alternative method for routine aneuploidy assessment of embryos that would be more comprehensive, cost-effective, and efficient. We speculated that aneuploidy could be readily assessed in test single-cell biopsy samples by first performing whole genome amplification followed by library generation, massively parallel shot-gun sequencing, and finally bioinformatics analysis to quantitatively compare the ratio of uniquely mapped reads to reference cells. Using Down syndrome as an example, the copy number change for chromosome 21 was consistently 1.5-fold higher in multiple cell and single-cell samples with a 47,XX,+21 karyotype. Applying the validated sequencing strategy to 10 sister blastomeres from a single human embryo, we showed that the aneuploidy status called by sequencing was consistent with short tandem repeat allelic profiling. These validation studies indicate that aneuploidy detection using sequencing-based methodology is feasible for further improving the practice of preimplantation genetic diagnosis.

Engineered chromosome-based genetic mapping establishes a 3.7 Mb critical genomic region for Down syndrome-associated heart defects in mice.

Trisomy 21 (Down syndrome, DS) is the most common human genetic anomaly associated with heart defects. Based on evolutionary conservation, DS-associated heart defects have been modeled in mice. By generating and analyzing mouse mutants carrying different genomic rearrangements in human chromosome 21 (Hsa21) syntenic regions, we found the triplication of the Tiam1-Kcnj6 region on mouse chromosome 16 (Mmu16) resulted in DS-related cardiovascular abnormalities. In this study, we developed two tandem duplications spanning the Tiam1-Kcnj6 genomic region on Mmu16 using recombinase-mediated genome engineering, Dp(16)3Yey and Dp(16)4Yey, spanning the 2.1 Mb Tiam1-Il10rb and 3.7 Mb Ifnar1-Kcnj6 regions, respectively. We found that Dp(16)4Yey/+, but not Dp(16)3Yey/+, led to heart defects, suggesting the triplication of the Ifnar1-Kcnj6 region is sufficient to cause DS-associated heart defects. Our transcriptional analysis of Dp(16)4Yey/+ embryos showed that the Hsa21 gene orthologs located within the duplicated interval were expressed at the elevated levels, reflecting the consequences of the gene dosage alterations. Therefore, we have identified a 3.7 Mb genomic region, the smallest critical genomic region, for DS-associated heart defects, and our results should set the stage for the final step to establish the identities of the causal gene(s), whose elevated expression(s) directly underlie this major DS phenotype.

Intracranial translucency at 11-13 weeks of gestation: prospective evaluation and reproducibility of measurements.

OBJECTIVE: This paper aimed to determine the feasibility of identification and measurement reproducibility of intracranial translucency (IT) in our population. METHODS: This is a prospective study in which five accredited operators attempted to identify and measure the IT during first-trimester sonographic screening for aneuploidy in 990 fetuses. The presence or absence of spina bifida was determined at the time of the second-trimester scan or after birth. Measurement reproducibility was assessed through intraclass correlation coefficient (ICC) on a subgroup of 150 fetuses. RESULTS: Identification and measurement of the IT were possible in 961 (97%) cases. The mean IT anteroposterior diameter was 1.8 mm (SD ± 0.37; range 0.8-3.1), and the size increased linearly with advancing gestation (IT = 0.74 + 0.02 × crown-rump length; r(2) = 0.15, p < 0.0001). The only fetus with spina bifida in this series presented with absent IT. Intra-observer and inter-observer ICCs were 0.79 and 0.75, respectively (95% confidence intervals 0.72-0.84 and 0.67-0.81, respectively; both p < 0.001). CONCLUSIONS: The IT increases linearly with increasing crown-rump length and seems to be of value in the first-trimester detection of spina bifida. It is easy to identify and measure and shows excellent intra-observer and inter-observer reproducibility measurements.

The absence of the vomer in the first and early second trimester of pregnancy - a new marker of trisomy 21 and trisomy 13.

PURPOSE: The aim of this study was to measure the two frontomaxillo-facial (FMF) angles: the FMF-vomer (FMF-v) and the FMF-palate (FMF-p), and to visualize the vomer in the 1(st) and early 2(nd) trimester, in order to ascertain whether they can be used as markers for trisomy 21 and trisomy 13. MATERIALS AND METHODS: A 2D ultrasound scan was performed in the 340 normal and 12 abnormal pregnancies, using the linear, convex and endovaginal probes. RESULTS: We visualized the FMF angles within 1 to 5 minutes in 253 (72 %) of cases by using the linear probe. FMF-v angle was significantly smaller that the FMF-p angle (79.8° vs. 89.7°, 71.5° vs. 84.5° for the two trimesters, respectively), and that the value of both angles decreased in the second trimester. There was not one single case of trisomy in which vomer could be identified in the 1 (st) and early 2 (nd) trimester. The FMF-p angle failed to present difference between normal cases and the ones with trisomy (89.5°). There was not one single case of trisomy (21 or 13) in which vomer or FMF-v could be identified in the first or early second trimester. The diagnostic accuracy of vomer as a marker for trisomy was 0.985. CONCLUSION: If the vomer cannot be visualized in the 1 (st) and early 2 (nd) trimester, it is important to check the karyotype, and it is not necessary to measure the FMF-p angle. The high resolution probe (L 12 - 5 Mhz) enables easier assessment of the vomer.

First-trimester screening for chromosomal abnormalities by integrated application of nuchal translucency, nasal bone, tricuspid regurgitation and ductus venosus flow combined with maternal serum free ß-hCG and PAPP-A: a 5-year prospective study.

OBJECTIVE: To investigate the performance of first-trimester screening for chromosomal abnormalities by integrated application of nuchal translucency thickness (NT), nasal bone (NB), tricuspid regurgitation (TR) and ductus venosus (DV) flow combined with maternal serum free ß-human chorionic gonadotropin (fß-hCG) and pregnancy-associated plasma protein-A (PAPP-A) at a one-stop clinic for assessment of risk (OSCAR). METHODS: In total, 13,706 fetuses in 13,437 pregnancies were screened for chromosomal abnormalities during a period of 5 years. Maternal serum biochemical markers and maternal age were evaluated in combination with NT, NT + NB, NT + NB + TR, and NT + NB + TR + DV flow data in 8581, 242, 236 and 4647 fetuses, respectively. RESULTS: In total, 51 chromosomal abnormalities were identified in the study population, including 33 cases of trisomy 21, eight of trisomy 18, six of sex chromosome abnormality, one of triploidy and three of other unbalanced abnormalities. The detection rate and false-positive rate (FPR) for trisomy 21 were 93.8% and 4.84%, respectively, using biochemical markers and NT, and 100% and 3.4%, respectively, using biochemical markers, NT, NB, TR and DV flow. CONCLUSION: While risk assessment using combined biochemical markers and NT measurement has an acceptable screening performance, it can be improved by the integrated evaluation of secondary ultrasound markers of NB, TR and DV flow. This enhanced approach would decrease the FPR from 4.8 % to 3.4 %, leading to a lower number of unnecessary invasive diagnostic tests and subsequent complications, while maintaining the maximum level of detection rate. Pre- and post-test genetic counseling is of paramount importance in either approach.

Health technology assessment and the media: more compatible than one may think?

While the Health Technology Assessment (HTA) community has acknowledged the importance of public and consumer involvement in the HTA process, very few studies have examined how technology-related findings may be reported by the media to the broader public. This paper compares the content of press articles with the content of three Canadian HTA reports that respectively assess electroconvulsive therapy, first-trimester prenatal screening for Down syndrome, and prostate-specific antigen screening for prostate cancer. We qualitatively and quantitatively analyzed 186 press articles addressing the same technologies. Our results show that beyond stylistic emphasis, there is an important overlap between media coverage of these technologies and the content of HTA reports. Findings also highlight shared interests on which both researchers and journalists could build to enhance the communication of health information to the public.

Alors que le milieu de l'évaluation des technologies de la santé (ETS) reconnaît l'importance du rôle du public et du consommateur dans les processus d'ETS, très peu d'études se sont penchées sur la présentation des résultats au grand public par les médias. Cette étude compare le contenu d'articles de presse avec celui de trois rapports canadiens sur l'ETS, qui évaluent respectivement l'électroconvulsivothérapie, le dépistage prénatal du syndrome de Down au premier trimestre et le test de dépistage de l'antigène prostatique spécifique pour le cancer de la prostate. Nous avons analysé qualitativement et quantitativement 186 articles de presse qui portent sur les mêmes technologies. Nos résultats montrent qu'au-delà des effets de style, il y a un important chevauchement entre la couverture des médias et le contenu des rapports. Les résultats soulignent également qu'il y a des intérêts partagés dont les chercheurs et les journalistes pourraient tirer profit afin de renforcer la communication d'information sur la santé au public.

Introduction of first trimester combined test increases uptake of Down's syndrome screening.

OBJECTIVE: To describe any trends in the uptake of antenatal screening for Down's syndrome since the addition of the earlier first trimester combined test. STUDY DESIGN: All antenatal screening tests for Down's syndrome were carried out and their results were recorded by the Clinical Biochemistry Department at the Hull Royal Infirmary (HRI) and reviewed against the antenatal booking data held at the Women and Children's Hospital at HRI. The uptake of antenatal Down's syndrome screening for 5 different age groups of women across a four-year-period from 2007 to 2010 was analysed. RESULTS: There was a significant increase in uptake of antenatal screening for Down's syndrome from 43.9% to 56.5% after the introduction of the combined test in 2010. This increase was apparent in all age groups. There was no change in the proportion of women opting for an invasive test following a positive screening test. CONCLUSION: Addition of the earlier first trimester combined test has increased uptake of antenatal screening for Down's syndrome in women of all ages. This is most likely due to the advantages this test gives women such as earlier decision making, earlier further invasive diagnostic testing and earlier termination, if necessary.

The cytogenetic examination as a tool for the diagnosis of chromosomal disorders / Examinación citogenética como herramienta para el diagnóstico de los desórdenes cromosómicos

Clinically significant chromosomal abnormalities occur in about 1 percent of children born alive. The objective of this work was to offer the patients and the families in the community for the service of the Integrated Clinic of Uniara Health (Araraquara and region), the examination of cariotype (cytogenetic study) for confirmation or exclusion of the diagnostic suspicion of chromosomal abnormalities as well as information (genetic counseling) for the prevention of occurrence and/or recurrence of these anomalies. In the period of one year and four months these were carried out in the Integrated Clinic of Uniara Health and directed for the Laboratory of Cytogenetic Human of the same institution in 66 cytogenetic studies. In 44 patients (66.6 percent) the results were normal. In 22 (33.3 percent) examinations, alterations were found, meaning that the respective clinical pictures are decurrent of chromosomic alterations. The first cause within alterations noted was Down syndrome with a total of 15 examinations or 68.1 percent, the second cause of chromosomal anomaly was the Turner syndrome where the most important factor is 45, X, where 2 karyotypes of this type or 9.1 percent were found, syndromes as (Eduards syndrome, Patau syndrome, 3p- syndrome, 4p- syndrome and 6p-syndrome) diagnosed in our laboratory appeared less frequently corresponding to 22.7 percent of the studied anomalies. The work carried out constitutes a necessary diagnosis of the main chromosomal abnormalities through a low cost technique; it can be carried out easily and is reliable, making the cytogenetic examination available to the community and contributing significantly to the quality of life of patients.

Las anormalidades cromosómicas, clínicamente significativas, se presentan en aproximadamente 1 por ciento de los niños nacidos vivos. Este trabajo tiene el objetivo de ofrecer a los pacientes y /o a sus familiares el servicio de la Clínica Integrada de la Salud de Uniara (Araraquara y Región), el examen de cariotipo (estudio citogenético) para la confirmación o la exclusión de sospecha de anomalías cromosomales diagnosticadas, así como otorgar información (consejo genético) para la prevención de las posibles anomalías y /o la repetición de éstas. En un año y cuatro meses fueron realizados 66 estudios de citogenética en la Clínica Integrada de Uniara, dirigida por el Laboratorio de Citogenética Humana de la misma institución. En 44 pacientes (66,6 por ciento) los resultados fueron normales. En 22 (33,3 por ciento) de los exámenes, se encontraron alteraciones, compatibles con alteraciones cromosómicas. La primera causa de anomalías cromosómica fue el síndrome de Down, totalizando 15 exámenes (68,1 por ciento), la segunda causa fue el síndrome de Turner, con dos cariotipos (9,1 por ciento) en la forma más importante 45, X. Por otra parte, se encontró que los síndromes de Eduards, de Patau, 3p-síndrome de Down, síndrome 4p-6p, diagnosticados en nuestro laboratorio, presentaban baja frecuencia de aparición, representando el 22,7 por ciento de las anomalías estudiadas. Este trabajo permitió realizar un diagnóstico preciso de las anomalías cromosomales, principalmente a través de una técnica de bajo costo, fácil ejecución y buena confiabilidad, técnicas que están disponibles para el examen citogenético para la comunidad y así contribuir de manera significativa en la calidad de vida de los pacientes.

APP-dependent up-regulation of Ptch1 underlies proliferation impairment of neural precursors in Down syndrome.

Mental retardation in Down syndrome (DS) appears to be related to severe neurogenesis impairment during critical phases of brain development. Recent lines of evidence in the cerebellum of a mouse model for DS (the Ts65Dn mouse) have shown a defective responsiveness to Sonic Hedgehog (Shh), a potent mitogen that controls cell division during brain development, suggesting involvement of the Shh pathway in the neurogenesis defects of DS. Based on these premises, we sought to identify the molecular mechanisms underlying derangement of the Shh pathway in neural precursor cells (NPCs) from Ts65Dn mice. By using an in vitro model of NPCs obtained from the subventricular zone and hippocampus, we found that trisomic NPCs had an increased expression of the Shh receptor Patched1 (Ptch1), a membrane protein that suppresses the action of a second receptor, Smoothened (Smo), thereby maintaining the pathway in a repressed state. Partial silencing of Ptch1 expression in trisomic NPCs restored cell proliferation, indicating that proliferation impairment was due to Ptch1 overexpression. The overexpression of Ptch1 in trisomic NPCs resulted from increased levels of AICD [a transcription-promoting fragment of amyloid precursor protein (APP)] and increased AICD binding to the Ptch1 promoter. Our data provide novel evidence that Ptch1 overexpression underlies derangement of the Shh pathway in trisomic NPCs with consequent proliferation impairment. The demonstration that Ptch1 overexpression in trisomic NPCs is due to an APP fragment provides a link between this trisomic gene and the defective neuronal production that characterizes the DS brain.

Cardiovascular development and survival during gestation in the Ts65Dn mouse model for Down syndrome.

The Ts65Dn mouse model for Down syndrome (DS) exhibits many phenotypes seen in human DS. Previous research has revealed a reduced rate of transmission of the T65Dn marker chromosome in neonates. To analyze potential fetal loss, litters from trisomic females at 10.5dpc through 14.5dpc were genotyped. No significant differences from the expected Mendelian ratio were found in transmission of T65Dn at any stage. Cardiovascular defects found in trisomic neonates are associated with formation of pharyngeal arch arteries. Vessel tracing was used to identify anomalies in 10.5dpc, 11.5dpc, and 13.5dpc embryos. Comparison of trisomic versus euploid embryos injected with India ink revealed delay and abnormality in cardiovascular development in trisomic embryos at each stage. Through the analysis of transmission rate and cardiovascular development in embryonic mice, we learn more about prenatal mortality and the origins of cardiac abnormality in the Ts65Dn mice to assist in understanding cardiovascular malformation associated with DS.

[Fetal hepatosplenomegaly in the third trimester: A sign of leukemia in fetuses with Down syndrome]. / Hépatosplénomégalie fœtale au troisième trimestre : un signe d'appel de leucémie chez les fœtus porteurs de trisomie 21.

Risk for leukemic conditions increases in individuals with Down syndrome. We report a third trimester antenatal diagnosis of leukemia in a Down syndrome fetus. The third trimester ultrasound examination revealed a hepatosplenomegaly, which may suggest a myelopoiesis disorder. A review of the literature of eight cases described antenatally and 14 cases in the immediate neonatal period is presented.

The performance of second trimester long bone ratios for Down syndrome screening is influenced by gestational age.

OBJECTIVE: To determine if gestational age (GA) at the time of ultrasound impacts the positive predictive value of shortened femur and humerus lengths (FL, HL) for trisomy 21 (T21). METHODS: Sonograms from 14 to 21 and 6/7 weeks' gestation were collected over a 28 month period. Multiple gestations or fetuses with major structural anomalies were excluded. Biometric data and GA were obtained; the expected HL (or FL): observed HL (or FL) ratios were calculated using two regression formulas (Benacerraf and Nyberg). A HL ratio <0.90 and a FL ratio <0.91 were considered shortened. T21 fetuses were identified through database and chart review. Positive predictive values (PPV) for T21 of the shortened bone ratios were determined, then stratified by GA. RESULTS: Of the 2606 ultrasounds, 8.9% and 18.9% of fetuses had shortened HL and FL ratios, respectively, using the Benacerraf formula. Shortened ratios were noted significantly less commonly (2.3 and 4.4%, respectively, P < 0.001 for each) using the Nyberg formula. With either formula, abnormal bone ratios were more frequently documented with a GA less than 17 weeks (P < 0.001). There were 17 T21 pregnancies. CONCLUSIONS: GA and formula selection influence the performance of long bone ratios as soft markers for T21 in the second trimester.

First trimester Down's syndrome screening marker values and cigarette smoking: new data and a meta-analysis on free beta human chorionic gonadotophin, pregnancy-associated plasma protein-A and nuchal translucency.

OBJECTIVES: To examine the effect of smoking on three first trimester screening markers for Down's syndrome that constitute the Combined test, namely nuchal translucency (NT), pregnancy-associated plasma protein-A (PAPP-A) and free beta human chorionic gonadotophin (free beta-hCG) and to use the results to determine which of these markers need to be adjusted for smoking and by how much. METHODS: The difference in the median multiple of the median (MoM) values in smokers compared to non-smokers was determined for NT, PAPP-A and free beta-hCG in 12,517 unaffected pregnancies that had routine first trimester Combined test screening. These results were then included in a meta-analysis of published studies and the effect of adjusting for smoking on screening performance of the Combined test was estimated. RESULTS: The results using the routine screening data were similar to the summary estimates from the meta-analysis of all studies. The results from the meta-analysis were; median MoM in smokers compared to non-smokers: 1.06 NT (95% confidence interval 1.03 to 1.10), 0.81 PAPP-A (0.80 to 0.83) and 0.94 free beta-hCG (0.89 to 0.99). The effect of adjusting for smoking on the Combined test is small, with an estimated less than half percentage point increase in the detection rate (the proportion of affected pregnancies with a positive result) for a 3% false-positive rate (the proportion of unaffected pregnancies with a positive result) and less than 0.2 percentage point decrease in the false-positive rate for an 85% detection rate. CONCLUSION: Adjusting first trimester screening markers for smoking has a minimal favourable effect on screening performance, but it is simple to implement and this paper provides the adjustment factors needed if a decision is made to make such an adjustment.