Detection Of Chromosomal Abnormalities Research Articles

Efficacy of copy-number variation sequencing technology in prenatal diagnosis.

Background Classical karyotyping and copy-number variation sequencing (CNV-seq) are useful methods for the prenatal detection of chromosomal abnormalities. Here, we examined the potential of using a combination of the two methods for improved and accurate diagnosis. Methods From February 2013 to January 2018, 64 pregnant women showing indications for fetal chromosomal examination in the affiliated hospital of the Inner Mongolia Medical University were selected for this study. Amniotic fluid was collected and used for karyotype analysis and CNV-seq. Results Karyotype analysis of the 64 cases showed that six cases (9.38%) had chromosomal abnormalities. Using CNV-seq, in addition to three cases with numerical abnormalities of chromosomes, 14 cases were detected with CNV, of which five were pathogenic CNV, four were of uncertain clinical significance and five were polymorphic CNV. However, CNV-seq failed to detect one case with sex chromosome mosaicism and a balanced translocation carrier. The rate of abnormal chromosome and CNV detection was 26.56% (17/64) by CNV-seq. Conclusion Application of CNV-seq in prenatal diagnosis could allow the detection of submicroscopic chromosomal abnormalities and effectively reduce the birth of children with microdeletion and microduplication syndrome. Additionally, the combined application of karyotype analysis and CNV-seq can effectively improve the detection rate of chromosome abnormalities.

Предпочтения беременных и врачей в выборе метода пренатального скрининга: мировой опыт

Многие страны внедряют неинвазивное пренатальное тестирование (НИПТ) в систему общественного здравоохранения в качестве контингентного скрининга для беременных, что позволяет повысить эффективность выявления хромосомных аномалий (ХА) у плода и снизить количество необоснованных инвазивных процедур. Анализ литературных источников показал, что большинство врачей и беременных из групп высокого и промежуточного рисков готовы воспользоваться НИПТ в качестве дополнительного скрининга в связи с его безопасностью, высокой чувствительностью и возможностью раннего получения результатов. Однако обнаружены различия в выборе метода раннего пренатального скрининга ХА между странами, которые зависели от этнических, социо-демографических и религиозных характеристик опрошенных, а также от особенностей политики местного здравоохранения, связанных с необходимостью частичной или полной оплаты пренатального теста и доступностью прерывания беременности. Сделан вывод, что для каждой страны необходимы свои руководства, разработанные с учетом социального контекста, а вопрос о внедрении НИПТ в рутинную практику должен решаться по результатам социологических исследований в больших группах беременных и врачей страны. Many countries are introducing a non-invasive prenatal test, NIPT, into the public health system as a contingent screening for pregnant women, which improves the detection of chromosomal abnormalities of the fetus and reduces the number of unwarranted invasive procedures. Analysis of the literature showed that the majority of doctors and pregnant women from the high and intermediate risk groups are ready to use NIPT as an additional screening due to its safety, high sensitivity and the possibility of early reception of results. However, there were found differences between countries in choosing the method of prenatal screening for chromosomal abnormalities of the fetus, which depend on the ethnic, sociodemographic and religious characteristics of the respondents, as well as on the peculiarities of the local health policy related to the need for partial or full payment of the prenatal test and the availability of abortion. It was concluded that each country needs its own guidelines, developed with taking into account the social context, and the issue of introducing NIPT into routine practice should be decided by the results of sociological research among large groups of pregnant women and healthcare professionals in the country.

Non-invasive Prenatal Sequencing for Multiple Mendelian Monogenic Disorders Using Circulating Cell-free Fetal DNA

(Abstracted from Nat Med 2019;25:439–447) Noninvasive prenatal screening has focused on the detection of chromosomal abnormalities in the fetus. At present, screening for many dominant monogenic disorders associated with de novo mutations is not available, despite their relatively high incidence.

Detection of chromosomal abnormalities in abortic tissues derived from patients with recurrent abortions using BoBs technique

To assess the value of BACs-on-Beads (BoBs) technique for the detection of chromosomal abnormalities in abortus tissues from recurrent pregnancy loss. A total of 109 abortus samples were collected and analyzed with the BoBs technique. The incidence and types of chromosomal abnormalities for different age groups and gestational weeks were compared. The BoBs assay has succeeded in all cases, with an incidence for chromosomal abnormalities reaching 62.39% (68/109). The major findings included trisomy 16 (12/68), trisomy 22 (9/68), trisomy 13 (9/68) and trisomy 21 (8/68). The abnormal rate was significantly higher in those above 35-year-old compared with that of the <35-year-old group (P<0.05). More aberrations were found among abortus tissues derived from 42-70 days of pregnancy albeit with no statistical significance (P>0.05). The aberration rates were similar for samples derived from second, third and fourth time abortions (P>0.05). BoBs technique can detect chromosomal aberrations in miscarriages and may be routinely used for the analysis of early spontaneous abortions.

"Immuno-flowFISH" for the Assessment of Cytogenetic Abnormalities in Chronic Lymphocytic Leukemia.

Imaging flow cytometry is emerging as a diagnostic tool for the assessment of leukemia. It has the functionality of standard flow cytometry and generates high-resolution digital images of each cell with quantifiable numerical data. We demonstrate the use of an automated high-throughput method for performing fluorescence in situ hybridization (FISH) on immunophenotyped whole cells in suspension and analyzed by imaging flow cytometry, a technique called "Immuno-flowFISH". The aim of this study was to demonstrate the application of immuno-flowFISH for the detection of chromosomal abnormalities in CLL, specifically trisomy 12 and del(17p). Mononuclear cells were isolated and immunophenotyped with fluorescently conjugated CD3, CD5, and CD19 monoclonal antibodies. Following fixation, cells were permeabilized, dsDNA denatured and hybridized with chromosome 12 or 17 enumeration (CEP 12 and CEP17) and 17p12 locus-specific FISH probes. Cells were analyzed on the Amnis ImageStream®X Mark II to assess the number and percent FISH-positive CLL cells and the ratio of FISH spot counts for CD5/CD19-positive CLL cells to CD3/CD5-positive T cells (FISH "mean spot ratio"). Deletion of 17p was detected in about 8% of cases to date, with del(17p) ranged from 3.5-22.8% and the FISH "mean spot ratio" 0.86-0.96. Immuno-flowFISH also detected a minimal residual disease case with +12 with a limit of detection of 0.13% and a rare case that presented with atypical phenotype and cytogenetics. Immuno-flowFISH could detect del(17p) in phenotypically identified CD5/CD19-positive B-cells. The 100-fold increase in analyzed cells, as well as the addition of cell phenotype increased the sensitivity and specificity over current clinical FISH testing. Furthermore, immuno-flowFISH analysis demonstrated specific utility in unique clinical scenarios such as residual disease and atypical biology cases which may be of significant benefit with regards to prognostication and MRD analysis. The method will assist in therapeutic decision making and disease monitoring for many hematological malignancies. © 2019 International Society for Advancement of Cytometry.

Investigation of the Effect of Decitabine on Hep-2 Cell Line at Chromosomal Level

DNA methylation is an epigenetic event that is defined as the binding of a methyl group via DNA methyl transferases (DNMTs) to the fifth carbon of cytosine in the CpG dinucleotide. Regulation of the expressions of tissue-specific genes, regulation of gene expressions during development, X inactivation and imprinting events are caused by DNA methylation. The aberrant DNA methylation associated with various diseases, especially cancers, is one of the most studied epigenetic mechanisms. Decitabine, a nucleoside analogue, inhibits DNMT enzymes and causes hypomethylation in the genome. There are many studies investigating the aberrant DNA methylation status in the genome of cells treated with Decitabine. Karyotype analysis is a cytogenetic method, which has been used successfully for the detection of both numerical and structural chromosomal abnormalities for many years. Hep-2 is a laryngeal cancer cell line, which is, used to investigate various genetic and epigenetic changes at the molecular level that revealed important information about the initiation and development of laryngeal cancer. However, the number of studies showing the chromosomal structure of Hep-2 cells is insufficient. The effects of Decitabine on cell morphology in different cell lines, its relationship with proliferation of the cells and its effects on chromosomes have been studied. However, the number of studies showing the effect of Decitabine at the chromosomal level in Hep-2 cell lines is also very limited. In current study, we investigated the chromosomes of Hep-2 cells cultured 72 hours with 1 μM and 10 μM Decitabine and without Decitabine. Keywords : Cell lines, Hep-2 cell line, Karyotyping, Decitabine, DNA methylation DOI : 10.7176/JSTR/5-4-11

Chromosomal microarray comparative genome hybridization (arrayCGH) in prenatal settings. Proposal for Hungarian application in clinical practice

Invasive prenatal testing and conventional G-banding chromosome analysis have been considered to be the gold standard of fetal cytogenetic diagnosis. Standard karyotyping is, however, constrained by the limits of the resolution of using a microscope. The advantage of molecular karyotyping, array based methods is the evaluation of sub-microscopic copy number changes across the whole genome in a single analysis. The application of array comparative genome hybridization has greatly increased the detection of pathogenic chromosomal abnormalities in prenatal settings. Based on available data in the international literature of the last decade, the clinical utility of arrayCGH is the recognition of some 1-2% and 5-7% additional genetical information compared to metaphase karyotype alone in fetuses without ultrasound anomaly and in fetuses with ultrasonographically detected malformations, respectively. Thus arrayCGH improves the prenatal diagnosis of genetic abnormalities mainly in fetuses with structural sonographic findings. In the present paper we review the literature of chromosomal microarray and make a proposal for the application of the method in Hungarian prenatal genetical practice. Orv Hetil. 2019; 160(13): 484-493.

Combined use of bacterial artificial chromosomes-on-beads with karyotype detection improves prenatal diagnosis

BackgroundThis study evaluated the individual and combined diagnostic performance of the bacterial artificial chromosomes (BACs)-on-Beads (BoBs™) assay and conventional karyotyping for the prenatal detection of chromosomal abnormalities in pregnant women who were 35 or more years-old.MethodThe primary outcome was concordance of any numerical, structural, or submicroscopic chromosomal abnormalities between BoBs™ and conventional karyotyping of amniotic fluid specimens from pregnant women at 17 to 22 weeks gestation.ResultsWe examined samples from 4852 pregnant women. BoBs™ indicated that 4708 samples were normal (97.03%), and 144 were abnormal (2.97%); conventional karyotyping indicated that 4656 (95.96%) samples were normal and 196 (4.04%) were abnormal. The combined use of both methods indicated that 4633 of 4852 samples were normal (95.49%) and 219 of 4852 samples (4.51%) were abnormal. The kappa coefficient of the combined test was 0.70, indicating substantial consistency between BoBs™ and conventional karyotyping (95% CI = 0.65–0.76, P < 0.001).ConclusionsOur results indicate that the combined use of BoBs™ and conventional karyotyping detected more fetal abnormalities than either test alone.

A new molecular screening tool for the detection of chromosomal abnormalities in donkeys.

Chromosomal abnormalities are a major cause of infertility and reproductive problems in equids. Nowadays, their detection is rising due to the use of new diagnostic tools based on molecular markers instead of karyotyping. Reports of this kind of genetic aberrations in domestic donkeys (Equus asinus) are extremely scarce, despite their importance in human activities. In the present study, we analysed the implementation of a short-tandem-repeat (STR)-based molecular method initially developed for horses, as a diagnostic tool to detect chromosomal abnormalities in donkeys. The frequency of five X-linked (LEX003, LEX026, TKY38, TKY270 and UCEDQ502) and one Y-linked (ECAYM2) molecular markers and one Y-linked gene (sex-determining region Y, SRY) was characterized in 121 donkeys from two diverse breeds, the Spanish Andalusian and the African Moroccan breeds. The molecular panel showed 100% sensitivity and 99.67% specificity in detecting 10 different chromosomal abnormalities in the species. In conclusion, this methodology is a valid, rapid and low-cost tool for the detection and characterization of chromosomal abnormalities in domestic donkeys.

Non-invasive prenatal sequencing for multiple Mendelian monogenic disorders using circulating cell-free fetal DNA.

Current non-invasive prenatal screening is targeted toward the detection of chromosomal abnormalities in the fetus1,2. However, screening for many dominant monogenic disorders associated with de novo mutations is not available, despite their relatively high incidence3. Here we report on the development and validation of, and early clinical experience with, a new approach for non-invasive prenatal sequencing for a panel of causative genes for frequent dominant monogenic diseases. Cell-free DNA (cfDNA) extracted from maternal plasma was barcoded, enriched, and then analyzed by next-generation sequencing (NGS) for targeted regions. Low-level fetal variants were identified by a statistical analysis adjusted for NGS read count and fetal fraction. Pathogenic or likely pathogenic variants were confirmed by a secondary amplicon-based test on cfDNA. Clinical tests were performed on 422 pregnancies with or without abnormal ultrasound findings or family history. Follow-up studies on cases with available outcome results confirmed 20 true-positive, 127 true-negative, zero false-positive, and zero-false negative results. The initial clinical study demonstrated that this non-invasive test can provide valuable molecular information for the detection of a wide spectrum of dominant monogenic diseases, complementing current screening for aneuploidies or carrier screening for recessive disorders.

Banding cytogenetics of the vulnerable species Houbara bustard (Otidiformes) and comparative analysis with the Domestic fowl.

The Houbara bustard Chlamydotisundulata (Jacquin, 1784) is an emblematic and endangered bird of steppes and desert spaces of North Africa. This species belonging to Otidiformes is recognized as vulnerable by the International Union for Nature Conservation.The critical situation of this species and the revision of its classification on the tree of birds encouraged the authors to start accumulating chromosome data. For that, we propose the GTG- and RBG-banded karyotypes of the Houbara bustard prepared from primary fibroblast cell cultures. The first eight autosomal pairs and sex chromosomes have been described and compared to those of the domestic fowl Gallusdomesticus (Linnaeus, 1758). The diploid number has been estimated as 78 chromosomes with 8 macrochromosomes pairs and 30 microchromosomes pairs, attesting of the stability of chromosome number in avian karyotypes.The description of the karyotype of the Houbara is of crucial importance for the management of the reproduction of this species in captivity. It can be used as a reference in the detection of chromosomal abnormalities, which would be responsible of the early embryonic mortalities.

Fluorescence in situ hybridization (FISH): History, limitations and what to expect from micro-scale FISH?

Abstract In this article, we review an important cytogenetic technique - fluorescence in situ hybridization (FISH) - which is used for obtaining spatial genomic and transcriptomic information. FISH is widely utilized in genomic and cell biological research as well as for diagnostic applications in preventive and reproductive medicine, and oncology. It is the gold standard technique for the detection of chromosomal abnormalities. Despite the high specificity of FISH and the possibility of direct quantitative imaging, some of its key limitations prevent its regular use in diagnostics. To promote the extensive use of FISH for these applications, limitations in assay time and probe consumption will need to be addressed. Microfluidic technologies hold great promise in improving exactly these parameters. In the past two decades, microtechnology has matured and enabled a new line of analysis tools for biomedical and chemical sciences. Incidentally, the convergence of microtechnology with microfluidics is starting to have a decisive impact in the field of medical diagnostics. By miniaturizing implementations of diagnostic assays, the special characteristics of fluid flow in small volumes can be leveraged to modify reaction kinetics and thus reagent delivery time of assays. Here we highlight selected important historical views on FISH, review its current implementations, and provide a perspective on the future developments and the micro-scale implementations of FISH.

The Value of Detailed First-Trimester Ultrasound Anomaly Scan for the Detection of Chromosomal Abnormalities.

To evaluate the performance of first-trimester ultrasound screening involving a detailed anomaly scan for the detection of trisomy 18, trisomy 13, triploidy, Turner syndrome and trisomy 21. Data of pregnant women who underwent aneuploidy screening at 11-13 weeks of gestation was retrospectively analyzed. Crown-rump length (CRL), fetal nuchal translucency thickness (NT) and nasal bone (NB) anatomy, blood flow across the tricuspid valve (TV) and through the ductus venosus (DV) were assessed. Furthermore, a detailed scan for fetal anatomical anomalies (FA) was carried out. Performance of these markers was assessed by logistic regression and ROC analyses for different screening models. 4005 fetuses were analyzed. 3856 were euploid, 149 aneuploid (trisomy 18: 40; trisomy 13: 14; triploidy: 3; Turner syndrome: 17; trisomy 21: 75 cases). 70-100 % of the fetuses with trisomy 18 and 13, triploidy and Turner syndrome but only 34.7 % with trisomy 21 had at least one fetal defect. Considering all aneuploidies, the detection rate (DR) for screening based on MA+NT+NB+TV+DV was 90.6 % and improved to 96.0 % if an FA was added (fixed false-positive rate: 3 %). If screening was based on MA+NT+FA, the detection rate for all aneuploidies was 85.2 %. However, the DR for trisomy 18, trisomy 13, triploidy and Turner syndrome (excluding trisomy 21) was 94.6 %, indicating the high diagnostic value of an anomaly scan for these aneuploidies. Incorporation of a detailed fetal anomaly scan (FA) into first-trimester screening algorithms can improve the detection rates for trisomy 18 and 13, triploidy and Turner syndrome.

Detection of DNA in Human Blastocyst Cavity Aspirate by Multiplex PCR

Preimplantation genetic testing (PGT) is a modern method of detection of chromosomal and genetic abnormalities in a human embryo before its transfer to the uterus. The genetic material is obtained by embryo biopsy. Here, we attempted to evaluate the efficiency of a method of noninvasive biopsy—aspiration of the blastocoel contents (blastocentesis) of human embryos. In this study, a biopsy was carried out human embryos with low morphological characteristics (3–4 CC according to Gardner grading) on day 6–7 of development. DNA obtained from the aspirate, as well as from the blastocyst, was analyzed by QF-PCR (quantitative fluorescent polymerase chain reaction) after whole genome amplification. In total, 24 blastocysts and aspirate samples obtained from them were analyzed; assayable DNA was found in seven (29%) aspirate samples from the blastocyst cavity, and this DNA was identical to blastocyst DNA in five (71%) cases. Thus, it was shown that, using aspiration of the blastocoel fluid of the human embryo, it is possible to obtain DNA suitable for analysis by molecular genetic methods. The features and advantages of the use of multiplex QF-PCR method combined with whole genome amplification for studying DNA obtained during aspiration of the blastocoel fluid are discussed. The prospects of DNA obtainment by the noninvasive biopsy method for preimplantation genetic testing (PGT) in the routine practice of infertility treatment and prevention of chromosomal and genetic abnormalities in newborns are considered.

Multiple occurrence of psychomotor retardation and recurrent miscarriages in a family with a submicroscopic reciprocal translocation t(7;17)(p22;p13.2)

BackgroundBalanced reciprocal chromosomal translocations (RCTs) are the ones of the most common structural aberrations in the population, with an incidence of 1:625. RCT carriers usually do not demonstrate changes in phenotype, except when the translocation results in gene interruption. However, these people are at risk of production of unbalanced gametes during meiosis, as a result of various forms of chromosome segregation. This may cause infertility, non-implantation of the embryo, shorter embryo or foetus survival, as well as congenital defects and developmental disorders in children after birth.The increasing popularity of cytogenetic molecular techniques, such as microarray-based CGH (aCGH), contributed to the improved detection of chromosomal abnormalities in patients with intellectual disability, however, these modern techniques do not allow the identification of the balanced in potential carriers. Therefore, classical chromosome analysis with GTG technique still plays an important role in the identification of balanced rearrangements in every case of procreation failure.Case presentationIn this article, a family with multiple occurrences of 17p13.3 duplication syndrome in the offspring and multiple miscarriages resulting from carrying of the balanced reciprocal translocation t(7;17)(p22;p13.2) by proband father is presented.The aCGH diagnostics allowed the identification of an unbalanced fragment responsible for the occurrence of clinical signs in the female patient, while karyotyping and FISH using specific probes allowed the localization of the additional material in the patient chromosomes, and identified the type of this translocation in the carriers.ConclusionsIdentification of a balanced structural aberration in one of the partners allows direct diagnostics for the exclusion or confirmation of genetic imbalance in the foetus via traditional invasive prenatal diagnostics. It is also possible to use an alternative method, Preimplantation Genetic Diagnosis (PGD) after in vitro fertilization, which prevents initiating pregnancy if genetic imbalance is detected in the embryo.

Recent advances in cytogenetic characterization of multiple myeloma

The detection of cytogenetic abnormalities in multiple myeloma (MM) has received more importance over last years for risk stratification and the new risk-adapted treatment strategies. Conventional G-banding analysis should be included in a routine procedure for the initial diagnostic workup for patients suspected of MM. However, the detection of chromosomal abnormalities in MM by conventional cytogenetics is limited owing to the low proliferative activity of malignant plasma cells as well as the low number of plasma cells in bone marrow specimens. Fluorescence in situ hybridization (FISH) or microarray-based technologies can overcome some of those drawbacks and detect specific target arrangements as well as chromosomal copy number changes. In this review, we will discuss different cytogenetic approaches and compare their strength and weakness to provide genetic information for risk stratification and prediction of outcome in MM patients.

Abstract 414: Broad range chromosomal abnormality detection through Bionano genome mapping

Abstract Current methods for detection of balanced structural variation can be broken down into two categories: traditional cytogenetics and molecular methods. Cytogenetics may include chromosomal karyotyping, fluorescence in situ hybridization (FISH), chromosomal microarray and adaption of them. Molecular methods primarily include NGS sequencing based methods. Bionano genome mapping, an optical mapping approach in a NanoChannel array system, is a method that combines the advantages of different categories while solving many of the limitations. Compared to cytogenetics, Bionano mapping is high throughput and removes manual interpretation, it also has much higher resolution, detecting balanced events as small as about 30 kbp compared to multi-megabases needed for cytogenetic approaches, and unbalanced events starting at 1 kbp. NGS based methods often are limited by read lengths that cannot provide unambiguous information across repeat elements longer than individual reads. This limitation results in significantly reduced sensitivity for balanced variation and abnormalities as well as for insertions and even some categories of larger deletions. This is particularly true in highly medically relevant locations where segmental duplications mediate chromosomal abnormalities. Genome mapping using Bionano Genomics' Saphyr System offers high-throughput, genome-wide visualization of extremely long DNA molecules in their native form. It allows researchers to interrogate genomic structural variations (SVs) in the range of one kilobase pair and above. We present several in silico and biological validation experiments that demonstrate the sensitivity and specificity of Bionano mapping for the detection of insertions, deletions, inversions and translocations compared to benchmark studies using short read and long read sequencing. We also show a new direct labeling method that dramatically improves assembly contiguity such that chromosome arms can be assembled into single maps. Bionano mapping is a fast and cost effective method for the detection of a broad range of traditionally refractory SVs across the human genome. Citation Format: Alex R. Hastie. Broad range chromosomal abnormality detection through Bionano genome mapping [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 414.

Next generation sequencing as a new detection strategy for maternal cell contamination in clinical prenatal samples.

The maternal cell contamination in chorionic villus or amniotic fluid presents a serious preanalytical risk for prenatal misdiagnosis. The following study presents and validates a novel process for identifying MCC by detecting short tandem repeat markers on Ion Proton system. Initially, MCC testing was performed during the detection of chromosomal abnormalities so as to improve the detection efficiency and accuracy of this method. More than 70 STR loci were selected to establish the detection progress. Capillary electrophoresis was used to compare the next generation sequencing detection results, as well as to identify the optimal STR on Ion Proton system. Evaluation criteria for maternal cell contamination were set, and the automated data analysis was performed. The detection sensitivity was validated via 4 groups with mixed samples and different proportions. Consequently, twenty-three clinical samples were tested to evaluate the detection accuracy. In addition, 14 reli-able STR loci, which were stably detected in more than 25 samples, were found. The detection sensitivity in maternal cell contamination was no less than 20%, while its accuracy reached 100% in clinical samples. Finally, we established and validated a novel detection procedure for maternal cell contamination in clinical prenatal samples using next generation sequencing. This procedure allowed us to simultaneously perform prenatal test-ing and MCC testing. Unlike the traditional capillary electrophoresis, this method is rapid, highly sensitive, and suitable for wide range of clinical applications.

Contemporary prenatal aneuploidy screening practice in Australia: Frequently asked questions in the cell-free DNA era.

Cell-free DNA screening has quickly become established in Australia as an accurate - albeit costly - prenatal screening test for trisomy 21, 18 and 13. It is also commonly used for the detection of sex chromosome abnormalities. The increasing number of prenatal screening pathways available to women has increased the complexity of pretest counselling. Concurrent advances in diagnostic testing with the widespread use of chromosomal microarrays create further challenges for the continuing education of clinicians and health consumers. This article aims to answer common clinical questions in this rapidly evolving field and complements the recently updated Royal Australian and New Zealand College of Obstetricians and Gynaecologists Statement on Prenatal Screening for Fetal Chromosome and Genetic Conditions.

P96: Detection of chromosome abnormalities using current noninvasive prenatal testing: A multi‐center comparative study

P96: Detection of chromosome abnormalities using current noninvasive prenatal testing: A multi‐center comparative study