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Objective: To assess whether the cisterna magna (CM) width measured in first-trimester fetuses is a useful marker for aneuploidy detection.Methods: This was a prospective study in 2 different cohorts in a tertiary referral center. The first cohort comprised 913 fetuses from the general pregnancy population during the period 2012-2016 and was used to construct the CM reference ranges applying the λ-μ-σ (LMS) method. The second cohort included 714 high-risk fetuses undergoing chorionic villus sampling during the period 2012-2016. Mean detection rates using the 95th percentile for CM width observed in chromosomal anomaly groups were compared with those obtained in chromosomally normal fetuses.Results: The 50th percentile for CM ranged from 1.66 to 2.75 mm when crown-rump length (CRL) increased from 45 to 84 mm. Among high-risk fetuses, the following chromosomal anomalies were diagnosed in 125 (17%) fetuses: trisomy 21 (n = 63), trisomy 18 or 13 (n = 21), monosomy X (n = 9), submicroscopic anomalies (n = 11), and other anomalies (n = 22). The mean CM width for euploid fetuses was 2.4 mm (1.13 multiples of the median, MoM). While CM width was significantly increased in trisomy 21 (mean 2.7 mm; 1.23 MoM; p > 0.05), no differences were found in the other anomaly groups. Among the 63 fetuses with trisomy 21, a CM width above the 99th percentile was observed in 23 fetuses (37%).Conclusions: The new reference range for CM width at 11-13 weeks of gestation did not differ from previous studies. In first-trimester fetuses with trisomy 21, CM width appears to be increased, although its value as an ultrasound marker is limited, because of its detection rate of 37%. [ABSTRACT FROM AUTHOR]

Introduction: The aim was to investigate the parental decisions about prenatal screening and diagnosis among infants with trisomy 21 (T21) in a national cohort with high uptake of combined first-trimester screening (cFTS).Material and Methods: This was a nationwide population-based study including infants born in 2009-2012. Information from the cFTS, fetal karyotype results and pregnancy outcome was obtained from the Danish Fetal Medicine Database on all women with a cFTS risk assessment. Cut-off for referral for invasive testing was ≥1:300. Karyotype results from pregnancies with no cFTS were obtained from the Danish Cytogenetic Central Registry.Results: The uptake rate of cFTS was 91.6%, and 82.8% (8,032/9,704) of the screen-positive women opted for invasive testing. Overall, 82.2% (454/552) chose to terminate an affected pregnancy. In the 4-year period, 102 of 232,962 singletons were born alive with T21. The cFTS risk was true-positive, false-negative or not obtained in 21.6, 48.0 and 30.4%, respectively, of these pregnancies.Discussion: In this large national cohort, 4.4 per 10,000 live-born infants had T21. Of 102 infants with T21 from 2009 to 2012, 52.0% were born after the women had not opted for cFTS or were true-positive but declined invasive testing or termination, and 48.0% were born after a false-negative risk assessment. [ABSTRACT FROM AUTHOR]

Background: Down syndrome, the most common birth defect, is caused by trisomy 21. The aim of this study was to investigate whether quantitative real-time PCR can be used as a sensitive technique for prenatal diagnosis of Down syndrome. Methods: We used a quantitative real-time PCR technique to measure the gene dosage of the Down syndrome critical region (DSCR3) by calculating the ratio of DSCR3 to GAPDH using standard curves. Sex-determining region Y was simultaneously detected by real-time PCR to identify the sex of the fetus. Results: The DSCR3/GAPDH ratio of the trisomy 21 fetus samples and that of normal controls was 0.72 ± 0.34 and 0.54 ± 0.18, respectively. Conclusion: In this study, there was no significant difference in the DSCR3/GAPDH ratio between the fetal and peripheral blood DNA samples of trisomy 21 fetuses and those of normal controls. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Objective: A fetus having partial trisomy of the distal part of chromosome 21q due to a de novo translocation is reported here. Method: A 29-year-old woman received amniocentesis at 18 weeks of gestation because of abnormal ultrasound findings including bilateral choroid plexus cysts, atrioventricular septal defects, rocker-bottom feet, and possible hydrocephalus. Results: Cytogenetic analysis revealed 46,XY, add(1)(p36.3), in which an additional material of unknown origin was attached to one of the terminal short arms of chromosome 1. Parental blood studies showed normal karyotypes in both parents. Spectral karyotyping was then performed and the origin of the additional material locating at chromosome 1p was found to be from chromosome 21. Conventional fluorescence in situ hybridization analysis was also used and confirmed the spectral karyotyping findings by use of a chromosome 21 specific painting probe, a locus specific probe localized within bands 21q22.13-q22.2 and a 21q subtelomeric probe. A hidden Down syndrome caused by a de novo translocation in this fetus was therefore diagnosed and the karyotype was designated as 46,XY, der(1)t(1;21)(p36.3;q22.1).ish der(1)(WCP21+, LSI 21+, 1pTEL-, 21q TEL+) de novo. Clinical features of the 1p36 deletion syndrome are also reviewed and may contribute to some features of this fetus. Termination of pregnancy was performed at 20 weeks of gestation. Conclusion: To our knowledge, our case appears to be the first to have partial monosomy 1p and partial trisomy 21q caused by de novo translocation being diagnosed prenatally. [ABSTRACT FROM AUTHOR]