Detection Of Common Aneuploidies Research Articles

Non-invasive Prenatal Testing in Pregnancies Following Assisted Reproduction.

In the decade since non-invasive prenatal testing (NIPT) was first implemented as a prenatal screening tool, it has gained recognition for its sensitivity and specificity in the detection of common aneuploidies. This review mainly focuses on the emerging role of NIPT in pregnancies following assisted reproductive technology (ART) in the light of current evidence and recommendations. It also deals with the challenges, shortcomings and interpretational difficulties related to NIPT in ART pregnancies, with particular emphasis on twin and vanishing twin pregnancies, which are widely regarded as the Achilles' heel of most pre-natal screening platforms. Future directions for exploration towards improving the performance and extending the scope of NIPT are also addressed.

Performance of Cell-Free DNA Screening for Fetal Common Aneuploidies and Sex Chromosomal Abnormalities: A Prospective Study from a Less Developed Autonomous Region in Mainland China.

To evaluate the performance of noninvasive prenatal screening (NIPS) in the detection of common aneuploidies in a population-based study, a total of 86,262 single pregnancies referred for NIPS were prospectively recruited. Among 86,193 pregnancies with reportable results, follow-up was successfully conducted in 1160 fetuses reported with a high-risk result by NIPS and 82,511 cases (95.7%) with a low-risk result. The screen-positive rate (SPR) of common aneuploidies and sex chromosome abnormalities (SCAs) provided by NIPS were 0.7% (586/83,671) and 0.6% (505/83,671), respectively. The positive predictive values (PPVs) for Trisomy 21, Trisomy 18, Trisomy 13 and SCAs were calculated as 89.7%, 84.0%, 52.6% and 38.0%, respectively. In addition, less rare chromosomal abnormalities, including copy number variants (CNVs), were detected, compared with those reported by NIPS with higher read-depth. Among these rare abnormalities, only 23.2% (13/56) were confirmed by prenatal diagnosis. In total, four common trisomy cases were found to be false negative, resulting in a rate of 0.48/10,000 (4/83,671). In summary, this study conducted in an underdeveloped region with limited support for the new technology development and lack of cost-effective prenatal testing demonstrates the importance of implementing routine aneuploidy screening in the public sector for providing early detection and precise prognostic information.

Rapid prenatal aneuploidy detection of BACs-on-Beads assay in 4961 cases of amniotic fluid samples

Objective To evaluate the diagnostic value of the BACs-on-Beads (BoBs) assay for the rapid diagnosis of common aneuploidies and microdeletions. Methods A total of 4961 pregnant women admitted to the Wuxi Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University from January 2017 to March 2019 were enrolled. BoBs assay and conventional karyotyping were applied to detect amniotic fluid samples with various indications for prenatal diagnosis. Chromosomal microarray analysis (CMA) and maternal cell contamination (MCC) tests were used for further validation. Results The overall abnormality detection rates (BoBs associated with karyotyping) were 4.25% (211/4961). The prenatal diagnosis success rate of karyotyping was 99.4% (4933/4961), compared to 100% (4961/4961) using the BoBs assays. The BoBs assay was similar to karyotyping for the detection of trisomy 21 (1.01%, 50/4961), trisomy 18 (0.40%, 20/4961), trisomy 13 (0.04%, 2/4961), and sex chromosomal aneuploidies (0.15%, 12/4961). The BoBs assay also identified sex chromosomal microduplications/microdeletions (1.73%, 86/4961), 22q11.2 microdeletions/microduplications (0.1%, 5/4961), and Cri du Chat syndrome (0.02%, 1/4961) which were missed by karyotyping. The sensitivity for the detection of numerical chromosomal abnormalities of the BoBs assay and karyotyping analysis was 100% (95/95, 95% CI: 1.0–1.0) and 98.9% (94/95, 95% CI: 0.969–1.010), respectively. The sensitivity of detecting structural chromosomal abnormalities in the BoBs assay was significantly higher than those of karyotyping (79.3%, 92/116, 95% CI: 0.718–0.868) versus 21.6% (25/116, 95% CI: 0.140–0.291) (p < .01). Conclusions The BoBs assay is a reliable and rapid test for the detection of common aneuploidies and nine microdeletion syndromes with high sensitivity and accuracy in prenatal diagnosis. The assay can compensate for the limitations of karyotyping analysis.

The importance of determining the limit of detection of non-invasive prenatal testing methods.

Several non-invasive prenatal testing (NIPT) methods, which analyze circulating fetal cell-free DNA (cfDNA) in maternal plasma, suggest a fetal fraction (FF) ≥ 4% for a reportable result, with the assumption that fetal aneuploidies may not be detectable at lower FF. This study determined the actual limit of detection (LOD) of a massively parallel sequencing-based NIPT method and evaluated its performance in testing samples with low FF. An experimental model, involving the creation of artificial plasma mixtures with a final aneuploid FF ranging from 1% to 4%, simulated samples at different proportions of fetal cfDNA. We then analyzed 7103 blood samples, from pregnant women undergoing NIPT, to assess the impact of low FF on the performance of cfDNA testing. Detection of common aneuploidies in samples with an FF as low as 2% is well within the ability of this technology. Of 105 pregnancies confirmed chromosomally abnormal, 25 (23.8%) involving a 2% < FF < 4% were consistently detected. These high-risk pregnancies would have not been identified using the suggested 4% FF cut-off. This study underscores the importance of determining the actual LOD for each specific NIPT methodology. It may reduce the incidence of test cancelations and shorten the time required for the diagnosis of aneuploidy. © 2016 John Wiley & Sons, Ltd.

The First Case Report in Italy of Di George Syndrome Detected by Noninvasive Prenatal Testing.

Panorama Plus (Natera), a single-nucleotide polymorphism- (SNP-) based approach that relies on the identification of maternal and fetal allele distributions, allows the detection of common aneuploidies and also incorporates a panel of 5 microdeletions including Di George syndrome. We report here the first case of Di George syndrome detected by NIPT in Italy; blood was drawn at 12 weeks' gestation. The patient had an amniocentesis to confirm the diagnosis by MLPA (multiplex ligation-dependent probe amplification) and an ultrasound aimed to detect the features associated with the syndrome. A right aortic arch and suspect of thymus atrophy were detected, but not other severe malformations typical of the disease. The patient terminated the pregnancy at 17 weeks. NIPT allowed an early screening of Di George syndrome. As the patient was at low risk, it is likely that an ultrasound would have missed the condition.

BACs-on-beads: a new robust and rapid detection method for prenatal diagnosis

Karyotyping, the gold standard used for diagnosis of chromosomal abnormalities, is being progressively replaced by rapid aneuploidy testing (RAT) techniques such as quantitative fluorescence-PCR, FISH and multiplex ligation-dependent probe amplification for diagnosing the common aneuploidies or chromosomal microarray analysis for comprehensive genome-wide testing. However, due to technical limitations, current RATs are confined to the detection of common aneuploidies 13, 18, 21 and sex chromosomes. To overcome the limitations of RATs, a bacterial artificial chromosomes-on-beads (BoBs™) assay technology has been introduced for the detection of the common aneuploidies as well as specific microdeletion syndromes. The BoBs assay is a bead-based multiplex assay using polystyrene beads impregnated with two spectrally distinct infrared fluorochromes to create a liquid array of up to 100 unique spectral signatures that supports the analysis of that scale of simultaneous hybridization assays on a minute DNA sample. This review gives an overview on the collective experiences of BoBs applications in prenatal diagnosis.

710: A targeted approach for the prenatal detection of common aneuploidies and 15 microdeletion syndromes

710: A targeted approach for the prenatal detection of common aneuploidies and 15 microdeletion syndromes

Conflicting results of prenatal FISH with different probes for Down's Syndrome critical regions associated with mosaicism for a de novo del(21)(q22) characterised by molecular karyotyping: Case report

For the rapid detection of common aneuploidies either PCR or Fluorescence in situ hybridisation (FISH) on uncultured amniotic fluid cells are widely used. There are different commercial suppliers providing FISH assays for the detection of trisomies affecting the Down's syndrome critical regions (DSCR) in 21q22. We present a case in which rapid FISH screening with different commercial probes for the DSCR yielded conflicting results. Chromosome analysis revealed a deletion of one chromosome 21 in q22 which explained the findings. Prenatally an additional small supernumerary marker chromosome (sSMC) was discovered as well, which could not be characterised. Postnatal chromosome analysis in lymphocytes of the infant revealed complex mosaicism with four cell lines. By arrayCGH the sSMC was provisionally described as derivative chromosome 21 which was confirmed by targeted FISH experiments.

QF-PCR-based prenatal detection of common aneuploidies in the Czech population: Five years of experience

We present the results from the largest clinical application of QF-PCR for antenatal rapid aneuploidy detection (RAD) in routine prenatal diagnosis in the Czech Republic. QF-PCR was performed in addition to karyotyping (dual testing) in two settings: the first was a single multiplex reaction testing only trisomy 21 and amelogenin X/Y alleles in the second trimester screened positive cases (T21 test), and the second setting consisted of two multiplexes (2M test) for common aneuploidies (13, 18, 21, X and Y) in cases with other RAD indications such as ultrasound findings, late booking or maternal anxiety. Dual testing was performed in 6349/12,778 (49.7%) of prenatal samples using either T21 or 2M test between 2002 and 2007. The clinical acceptability of our dual testing policy, methodological efficiency of RAD and residual risks of other chromosomal aberrations (CHAs) were evaluated. QF-PCR detected 92% (175/190) of significant CHAs. The 2M test identified 93.5% and the T21 test identified 87.5% of the significant CHAs with complete specificity. The residual risk of significant CHA was 1/231 in the 2M test and 1/565 in the T21 test. If RAD for all common aneuploidies is used as the sole prenatal diagnosis method, the odds of missing a CHA of any type are 1:90 and the odds of missing significant CHA with no ultrasound findings are 1:1513. If prenatal karyotyping were used as an additional procedure to RAD in cases only with ultrasound findings, 186/190 (97.8%) of the significant CHAs would be detected when 15.7% cases were karyotyped, according to our data. We consider RAD directed towards trisomy 21 alone (our T21 test) as an economically and clinically acceptable part of second trimester screening for Down syndrome. Both RAD tests allow fast alleviation of maternal anxiety with low residual risk when the test results are negative, and allow fast decision making if the results are positive. However, replacement of dual testing with only the RAD procedure in specific indications accepted in some countries (Great Britain) remains in the Czech Republic a theme for debate.

576: Comparison of CVS chromosome analysis with interphase fish in the detection of common aneuploidies

To compare the accuracy of interphase FISH with cytogenetic analysis in detecting common chromosome abnormalities in CVS samples. The Genzyme database was queried for CVS specimens analyzed from 1997-07 in which both FISH for chromosomes 13, 18, 21, X & Y (INSIGHT; Aneuvysion, Abbott) and cytogenetic analysis of cultured chorionic villi were available. 823 chromosome abnormalities were found among 4.524 specimens (18%). Aneuploidy for 13, 18, 21, X & Y was identified in 687/823 abnormal specimens (83.5%). The remaining 136 aneuploid results involved other chromosome abnormalities and represented 16.5% of all aneuploidy. There was a 98% concordance between INSIGHT and cytogenetic results. Of the 14 discrepancies, most were due to tissue specific (cytotrophoblastic) mosaicism. There were 6 false positive results (CVS chromosome analysis normal, INSIGHT abnormal) with 4 due to tetraploidy, a common, clinically insignificant finding and one case each of trisomy 13 and monosomy 18. INSIGHT and cytogenetic results have a 98% concordance for abnormalities of chromosomes 13, 18, 21, X & Y found on CVS. The concordance is 76/81 (93.8%) for sex chromosome abnormalities, 26/27 (96.3%) for polyploidy, and 571/578 (98.8%) for trisomies 13, 18, & 21. False negatives occur in 2% and false postives are rare. Although INSIGHT is a reliable test for expeditious analysis of CVS samples, irreversible actions should not be based on INSIGHT results alone.Tabled 1Karyo-typeCulturesINSIGHT +INSIGHT −Detection45X6562395.4%XXY65183.3%XYY220100%XXX87187.5%Triploid26260100%Tetraploid1010%T1360600100%T18165162398.2%T21354349598.6%TOTAL6876731498.0% Open table in a new tab

Sex chromosome rearrangements leading to partial aneuploidies and mosaicisms: use of QF-PCR for detection and quantification of the involved cell lines.

Chromosome rearrangements can lead to aneuploidies of specific chromosome regions and could be present in the entire individual or limited to some tissues (mosaicism) depending on the developmental stage of the embryo when the rearrangement occurs. We report 6 cases with sex chromosome rearrangements identified by conventional cytogenetics and tested by quantitative fluorescent polymerase chain reaction (QF-PCR). QF-PCR has been largely employed for rapid detection of common aneuploidies in pre-natal and post-natal diagnosis and consists in DNA amplification by polymerase chain reaction (PCR) using fluorescent labelled primers and the analysis of chromosome specific small tandem repeats (STR). We tested 5 sex chromosome specific STR markers in multiplex PCR amplifications together with other chromosome specific STR markers as control amplifications. The PCR products were analysed by capillary electrophoresis. The results from QF-PCR analysis were obtained within one day and confirmed our cytogenetic observations. This study shows that QF-PCR analysis can detect sex chromosome imbalance and also suspect mosaicism or chromosome rearrangement.