Sex Chromosome Abnormalities Research Articles

Prevalence and patterns of chromosomal abnormalities among Egyptian patients with infertility: a single institution\u2019s 5-year experience

BackgroundChromosomal abnormalities represent an important cause of human infertility. Little is known about the prevalence of chromosomal abnormalities among Egyptian couples with infertility. We estimated the cytogenetic profiles and semen analysis patterns among infertile couples. We analyzed data from medical archives of 2150 patients with infertility in Mansoura University Children’s Hospital, Egypt from 2015 to 2019. The data included karyotypes and semen analysis reports.ResultsChromosomal abnormalities were reported in 13.5% of infertile patients (290/2150); 150 out of 1290 (11.62%) males and 140 out of 860 (16.28%) females. Within the infertile males, the numerical chromosomal abnormalities were detected in 134/1290 (10.38%) males, and structural abnormalities were found in 16/1290 (1.24%) males. Within the infertile females, numerical sex chromosome abnormalities were detected in 75/860 (8.72%) females, structural sex chromosome abnormalities were found in 31/860 (3.6%) females, mosaicism of the sex chromosome was found in 22/860 (2.56%) females, and male pseudohermaphrodites were detected in 12/860 (1.39%) females.ConclusionsNumerical chromosomal aberrations are the most frequent patterns among infertile couples. Attention should be paid to the traditional chromosomal analysis as an important diagnostic step in the infertility work-up.

Practice of clinical application of noninvasive prenatal testing based on cell-free fetal DNA

To assess the application value of noninvasive prenatal testing (NIPT) based on cell-free fetal DNA. The results of 2777 cases of basic and extended NIPT were retrospectively analyzed. The clinical data and outcome of pregnancy were analyzed, in addition with the diagnosis rate and testing efficiency. Among the 2777 pregnant women, 1192 (42.9%) had accepted basic NIPT and 1585 (57.1%) accepted extended NIPT. With a failure rate of 0.1%, 8 and 6 cases were reported respectively as high-risk pregnancies for trisomy 21 and sex chromosomal abnormalities. Other genetic abnormalities were detected in 32 cases. The positive predictive value for trisomy 21 was 85.7%, and one case of 47,XXX was diagnosed among 3 women with high risks for sex chromosomal abnormalities. For those with a high risk for other genetic abnormalities, pregnant diagnosis rates of basic and extended NIPT were 71.4% (5/7) and 68.2% (15/22), respectively. Seven copy number variations (CNVs) were confirmed, including one pathogenic CNV, one likely pathogenic CNV and 5 variants of unknown significance. Among 6 cases with high-risk of maternal CNVs, 5 fetuses and the mothers were confirmed to be carriers. No CNV was detected in the remainder fetus by chromosomal microarray analysis, while its mother was a carrier of the corresponding CNV. NIPT has shown a relatively high positive predictive value for the screening of trisomy 21 and maternal CNVs but with a limited efficiency for the discovery of fetal CNVs. For other genetic abnormalities signaled by NIPT, informed choice by the pregnant women during pre-testing consultation is recommended. Invasive prenatal diagnosis should be considered in the combination of NIPT reports and fetal ultrasound, while the residual risks should be fully informed.

SeGMM: A New Tool for Gender Determination From Massively Parallel Sequencing Data.

In clinical genetic testing, checking the concordance between self-reported gender and genotype-inferred gender from genomic data is a significant quality control measure because mismatched gender due to sex chromosomal abnormalities or misregistration of clinical information can significantly affect molecular diagnosis and treatment decisions. Targeted gene sequencing (TGS) is widely recommended as a first-tier diagnostic step in clinical genetic testing. However, the existing gender-inference tools are optimized for whole genome and whole exome data and are not adequate and accurate for analyzing TGS data. In this study, we validated a new gender-inference tool, seGMM, which uses unsupervised clustering (Gaussian mixture model) to determine the gender of a sample. The seGMM tool can also identify sex chromosomal abnormalities in samples by aligning the sequencing reads from the genotype data. The seGMM tool consistently demonstrated >99% gender-inference accuracy in a publicly available 1,000-gene panel dataset from the 1,000 Genomes project, an in-house 785 hearing loss gene panel dataset of 16,387 samples, and a 187 autism risk gene panel dataset from the Autism Clinical and Genetic Resources in China (ACGC) database. The performance and accuracy of seGMM was significantly higher for the targeted gene sequencing (TGS), whole exome sequencing (WES), and whole genome sequencing (WGS) datasets compared to the other existing gender-inference tools such as PLINK, seXY, and XYalign. The results of seGMM were confirmed by the short tandem repeat analysis of the sex chromosome marker gene, amelogenin. Furthermore, our data showed that seGMM accurately identified sex chromosomal abnormalities in the samples. In conclusion, the seGMM tool shows great potential in clinical genetics by determining the sex chromosomal karyotypes of samples from massively parallel sequencing data with high accuracy.

EP469: Improved Vanadis NIPT platform for detection of T13 T18 and T21 and sex chromosome abnormalities

The American College of Obstetricians and Gynecologists (ACOG) is recommending prenatal aneuploidy screening for all pregnant patients regardless of age or other risk factors. To address this need, in 2021, we expanded our validation of the Vanadis cell free DNA (cfDNA) - a non-PCR based, and automated assay for the screening of trisomies 13, 18 and 21 - as a laboratory developed test (LDT) within our global laboratory sites in USA, Sweden, India, and Malaysia. We integrated the Vanadis cfDNA system and Vanadis LifeCycle reporting software with our Plus91 laboratory information management system for a simpler workflow, starting with intake of blood samples from pregnant women and finishing with clinical reports for >2000 cases.

Cohort profile: genomic data for 26 622 individuals from the Canadian Longitudinal Study on Aging (CLSA)

PurposeThe Canadian Longitudinal Study on Aging (CLSA) Comprehensive cohort was established to provide unique opportunities to study the genetic and environmental contributions to human disease as well as ageing process....

EP463: Inconclusive Duchenne Muscular Dystrophy (DMD) carrier screening and atypical SNP-based NIPS sex chromosomes analysis suggest maternal sex chromosome abnormality

As of 2021, ACMG has expanded the recommended carrier screening panel to constitute 113 genes, now including the X-linked Duchenne Muscular Dystrophy (DMD) gene. Copy number variant (CNV) analysis by next-generation sequencing (NGS) of DMD yields inconclusive results for a small number of individuals due to the duplication/deletion of all DMD exons and adjacent regions on the X chromosome. In addition, a small number of SNP-based noninvasive prenatal screening (NIPS) tests yield no results for sex chromosomes due to a suspected maternal X chromosome abnormality.

Development and validation of a novel 26-plex system for prenatal diagnosis with forensic markers.

Short tandem repeat (STR) loci are commonly used in forensic casework, such as personal identification and paternity testing. In recent years, STR has also been widely used for rapid, accurate and automated prenatal diagnosis, known as quantitative fluorescent PCR (QF-PCR). Despite their usefulness, the current systems often lack the power to detect mosaicism for Turner syndrome. In this study, we developed a novel 26-plex system that combined the 22 STRs in chromosome 21/18/13/X, 3 sex loci and 1 quality control marker (TAF9L). The system was generated to achieve greater diagnostic power of trisomy 21/18/13 and sex chromosome abnormalities. Studies of the sensitivity, specificity, stability and accuracy were performed according to the Scientific Working Group on DNA Analysis Methods (SWGDAM) guidelines. Compared with the results of the chromosomal microarray analysis (CMA)/copy number variation sequencing (CNV-seq), the detection ratio of non-mosaic chromosome abnormalities of this system in the identification of chromosome 21/18/13/X/Y aneuploidies reached 100%, and the rate of negative results was consistently 100% based on 203 prenatal diagnosis sample analyses. In addition, our results suggested that this panel was a useful tool for mosaicism for Turner syndrome cases. Interestingly, we found one case with large segment loss of chromosome X, which indicated that we should be alert to this situation when the STR genotype of the parent-child is inconsistent in forensic genetics. In summary, this study demonstrated that our system is an accurate, cost-effective and rapid approach for the detection of chromosome numerical abnormalities in prenatal diagnosis.

Cell-Free DNA Screening for Sex Chromosome Abnormalities and Pregnancy Outcomes, 2018-2020: A Retrospective Analysis.

To evaluate the efficacy of non-invasive prenatal screening (NIPT) for detecting fetal sex chromosome abnormalities, a total of 639 women carrying sex chromosome abnormalities were selected from 222,107 pregnant women who participated in free NIPT from April 2018 to December 2020. The clinical data, prenatal diagnosis results, and follow-up pregnancy outcomes of participants were collected. The positive predictive value (PPV) was used to analyze the performance of NIPT. Around 235 cases were confirmed with sex chromosome abnormalities, including 229 cases with sex chromosome aneuploidy (45, X (n = 37), 47, XXX (n = 37), 47, XXY (n = 110), 47, XYY (n = 42)) and 6 cases with structural abnormalities. The total incidence rate was 0.11% (235/222,107). The PPV of NIPT was 45.37% (235/518). NIPT accuracy for detecting sex chromosome polysomes was higher than that for sex chromosome monomers. The termination of pregnancy rate for fetal diagnosis of 45, X, and 47, XXY was higher than that of 47, XXX, and 47, XYY. The detection rate of fetal sex chromosome abnormalities was higher in 2018–2020 than in 2010–2012 (χ2 = 69.708, P < 2.2 × 10−16), indicating that NIPT is greatly efficient to detect fetal sex chromosome abnormalities.

Influence of fibroids on cell-free DNA screening accuracy.

Cell-free DNA (cfDNA) screening assesses both maternal and placental cfDNA. Fibroids are common and release cfDNA into maternal serum. Genetic abnormality is seen in 50% of fibroids. We aimed to assess the impact of fibroids on the accuracy of genome-wide cfDNA screening. This was a prospective cohort study of singleton pregnancies examined at one of two centers in Melbourne and Sydney, Australia, between 1 November 2019 and 31 December 2020. All cases underwent pretest ultrasound examination to confirm an ongoing pregnancy of at least 10 weeks' gestation, and, at this stage, the number and volume of any uterine fibroid were documented. Genome-wide cfDNA screening was performed to detect all copy-number variants (CNV) > 7 megabases. The incidence of a false-positive result was compared between cases with and those without fibroids. Over the 14-month study period, 13 184 patients underwent cfDNA screening, of whom 1017 (7.7%) had fibroids. Fibroids were not identified in any of the 17 participants who had a false-positive result for chromosomes 13, 18, 21, X or Y. Ninety-five (0.7%) cases were screen-positive for subchromosomal aberration (SA), rare autosomal trisomy (RAT) or multiple abnormalities (MA), with 10 of these cases having a fetal genetic abnormality. The incidence of a false-positive RAT, MA or SA result was significantly higher in participants with fibroids (20/1017 (2.0%)) than in those without fibroids (64/12 167 (0.5%)). Women with fibroids were approximately six times as likely to have a false-positive result for SA, and this was associated positively with both fibroid number and volume. Most women with fibroids do not have an abnormal result on genome-wide cfDNA screening. However, CNVs due to fibroids are associated with false-positive SA findings, although fibroids do not appear to influence cfDNA screening accuracy for the common autosomal trisomies or sex-chromosomal abnormalities. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Noninvasive Prenatal Screening Based on Second-Trimester Ultrasonographic Soft Markers in Low-Risk Pregnant Women.

Background: We aimed to assess the clinical application of noninvasive prenatal screening (NIPS) based on second-trimester ultrasonographic soft markers (USMs) in low-risk pregnant women. Methods: Data of pregnant women between April 2015 and December 2019 were retrospectively analyzed. Pregnant women [age at expected date of confinement (EDC) of <35 years; low risks for trisomy 21 (T21) and trisomy 18 (T18) based on maternal serum screening; presenting second-trimester USMs (7 types)] who successfully underwent NIPS and had available follow-up information were included in our study. Cases with positive NIPS results were prenatally diagnosed. All patients were followed up for 6 months to 2 years after NIPS, and their clinical outcomes were obtained. Subgroup analyses were performed according to the different USMs. Results: NIPS suggested that among a total of 10,023 cases, 37 (0.37%) were at high risk of aneuploidy, including 4 T21, 6 trisomy 13 (T13), and 27 sex chromosome abnormalities (SCA). Ten cases with aneuploidy (0.10%) were confirmed by prenatal diagnosis, consisting of two T21 and eight SCA. The eight fetuses with SCA consisted of one monosomy X, two XXY, one XXXY, one XXX, one XYY, and two mosaicisms. T21 was detected in one fetus with absent or hypoplastic nasal bone and one fetus with echogenic intracardiac focus (EICF). SCA was detected in five fetuses with EICF, two fetuses with multiple soft markers, and one fetus with echogenic bowel. The positive rate of chromosomal aneuploidy was significantly higher in fetuses with absent or hypoplastic nasal bone (6.25 vs. 0.10%, p = 0.017), echogenic bowel (3.7 vs. 0.10%, p = 0.029), and multiple soft markers (0.678 vs. 0.10%, p = 0.045) than in the total fetuses. The positive predictive values (PPVs) of NIPS in these three groups were 100%, 50%, and 100%, respectively. EICF accounted for 93.25% (9,346/10,023) of the study population, whereas the PPV of NIPS was only 20%. Conclusion: NIPS is an advanced screening test for low-risk pregnant women. In the 10,023 pregnant women sampled, SCA were more common than autosomal trisomy, and EICF was the most frequent USM but the least predictive aneuploidy. Further aneuploidy evaluation is suggested for low-risk pregnant women whose ultrasound indicates absent or hypoplastic nasal bone, echogenic bowel, or multiple soft markers. NIPS can serve as a second-line complementary screening for these women.

Analysis to the failure rate and causes of noninvasive prenatal testing based on high-throughput sequencing

To analyze the cause and pregnancy outcome for non-reportable cell-free DNA (cfDNA) results during non-invasive prenatal testing (NIPT). cfDNA was extracted from maternal plasma from 5898 singleton pregnancies at 12 to 22 gestational weeks and underwent NIPT with strict quality control standards. For those with sub-standard results, redraw or invasive prenatal procedures were recommended. Among the 5898 cases, 32 have failed for the initial NIPT, including 17 cases with substandard cffDNA%, 10 cases with data fluctuation after twice library constructing and sequencing, and 5 cases with unidentifiable sex chromosome abnormalities. For these 32 cases, 2 directly underwent amniocentesis, and karyotyping analysis showed both were normal. Six of the 30 redrawn cases finally turned out to be nonreportable. The final nonreportable rate was therefore 0.1% (8/5898). Of the redrawn cases, 1 trisomy 21, 1 trisomy 18 and 1 trisomy 13 high risk-cases were identified, which were all confirmed to be false positive. Among the 6 nonreportable cases, 2 women underwent invasive prenatal testing, and 1 was found to have a normal fetal karyotype, while another was found to have an abnormal karyotype of mos45,X[32]/46,XY[18]. The other 4 nonreportable cases who did not accept invasive prenatal testing have all reported normal child development at follow-up. The main reason for nonreportable NIPT results was low cffDNA%. The high success rate of the redrawn cases has effectively increased the overall NIPT success rate and reduced the number of the cases necessitating invasive prenatal diagnosis. The initially nonreportable women may consider retesting after careful counseling with informed consent.

Physiological and molecular sex differences in human skeletal muscle in response to exercise training.

Sex differences in exercise physiology, such as substrate metabolism and skeletal muscle fatigability, stem from inherent biological factors, including endogenous hormones and genetics. Studies investigating exercise physiology frequently include only males or do not take sex differences into consideration. Although there is still an underrepresentation of female participants in exercise research, existing studies have identified sex differences in physiological and molecular responses to exercise training. The observed sex differences in exercise physiology are underpinned by the sex chromosome complement, sex hormones and, on a molecular level, the epigenome and transcriptome. Future research in the field should aim to include both sexes, control for menstrual cycle factors, conduct large-scale and ethnically diverse studies, conduct meta-analyses to consolidate findings from various studies, leverage unique cohorts (such as post-menopausal, transgender, and those with sex chromosome abnormalities), as well as integrate tissue and cell-specific -omics data. This knowledge is essential for developing deeper insight into sex-specific physiological responses to exercise training, thus directing future exercise physiology studies and practical application.

Investigation on the genetic-inconsistent paternity cases using the MiSeq FGx system

Mutations might challenge the paternity index calculation in forensic identification. While many studies have focussed on the autosomal short tandem repeats (A-STR), the mutation status of sex chromosomes and single nucleotide polymorphism (SNP) remain blank. Next generation sequencing (NGS), known as high throughput and large sequence polymorphism, is a promising tool for forensic genetics. To describe the mutation landscapes in the paternity cases with genetic inconsistencies, a total of 63 parentage confirmed paternity cases contained at least one mismatched locus have been collected. The mutations were subsequently evaluated using Verogen’s MPS ForenSeqTM DNA Signature Kit and a microsatellite instability (MSI) detection kit. The result showed 98.41% (62/63) of the cases had no additional autosomal mutations even when the number of A-STRs increased to 27. As for the sex chromosomes, about 11.11% (7/63) of the cases exhibited either X-STR or Y-STR mutations. D2S1338, FGA and Penta E were the most frequent altered STRs, which suggested they might be the mutation hotspots. In addition, a male with sex chromosome abnormality was observed accidently, whose genotype might be 47, XXY, rather than MSI. Nearly 56.90% of the STR loci possessed isoalleles, which might result in higher STR polymorphisms. No Mendelian incompatibility was detected among the SNP markers, which indicated that SNP was a more reliable genetic marker in the genetic-inconsistent paternity cases. Supplemental data for this article is available online at https://doi.org/10.1080/20961790.2021.2009631 .

Molecular and Cytogenetic Analysis of Romanian Patients with Differences in Sex Development.

Differences in sex development (DSD) are often correlated with a genetic etiology. This study aimed to assess the etiology of DSD patients following a protocol of genetic testing. Materials and methods. This study prospectively investigated a total of 267 patients with DSD who presented to Clinical Emergency Hospital for Children Cluj-Napoca between January 2012 and December 2019. Each patient was clinically, biochemically, and morphologically evaluated. As a first intervention, the genetic test included karyotype + SRY testing. A high value of 17-hydroxyprogesterone was found in 39 patients, in whom strip assay analysis of the CYP21A2 gene was subsequently performed. A total of 35 patients were evaluated by chromosomal microarray technique, and 22 patients were evaluated by the NGS of a gene panel. Results. The karyotype analysis established the diagnosis in 15% of the patients, most of whom presented with sex chromosome abnormalities. Genetic testing of CYP21A2 established a confirmation of the diagnosis in 44% of patients tested. SNP array analysis was particularly useful in patients with syndromic DSD; 20% of patients tested presented with pathogenic CNVs or uniparental disomy. Gene panel sequencing established the diagnosis in 11 of the 22 tested patients (50%), and the androgen receptor gene was most often involved in these patients. The genes that presented as pathogenic or likely pathogenic variants or variants of uncertain significance were RSPO1, FGFR1, WT1, CHD7, AR, NIPBL, AMHR2, AR, EMX2, CYP17A1, NR0B1, GNRHR, GATA4, and ATM genes. Conclusion. An evaluation following a genetic testing protocol that included karyotype and SRY gene testing, CYP21A2 analysis, chromosomal analysis by microarray, and high-throughput sequencing were useful in establishing the diagnosis, with a spectrum of diagnostic yield depending on the technique (between 15 and 50%). Additionally, new genetic variants not previously described in DSD were observed.

Identification of genomic imbalances (CNVs as well as LOH) in sertoli cell only syndrome cases through cytoscan microarray.

Sertoli cell only syndrome (SCOS) is characterized by complete absence of germ cells in seminiferous tubules of testis. SCOS is multifactorial but genetic factors play a major role in pathogenesis of the disorder with idiopathic origin. Genetic factors majorly include sex chromosomal aneuploidy and Yq Microdeletion. But a large number of cases are still idiopathic. The study aimed to evaluate the genomic imbalances (CNVs and LOH) in idiopathic SCOS patients. The study is based on 28 apparent idiopathic SCOS cases and 10 controls. Molecular cytogenetic techniques viz., FISH, STS-Multiplex PCR and Affymetrix cytoscan microarray (750K) were used. The microarray screened whole genomic imbalances in DNA from peripheral blood of 25 cases (excluded Klinefelter syndrome patients) and testicular FNAC sample of 2 cases. High FSH and low Inhibin B were observed in cases as compared to control controls groups. Four cases of sex chromosomal abnormality (i.e., three non-mosaic 47, XXY males and one non-mosaic 46, XX male) as well as four cases of Yq microdeletion (i.e., three cases with AZFc deletion and one case with complete AZFa, b and c deletion) were identified. Microarray detected unbalanced translocation of two segments of Y-chromosome i.e., Yp11.31-p11.2 (~4.o mb region, involving SRY) and Yp11.2 (~2.5 mb region) on X-chromosome in XX male. Also, loss of segment on same X-chromosome involving PAR1 region was identified. We have identified both autosomal and sex chromosomal CNVs (recurrent as well as private) involving candidate genes like SYCE1, ZFPM2, SRPK1, DAZ1, BPY2, HSFY1, VCY1 etc. All these CNVs are possibly associated with SCOS pathogenesis. CNVs identified in cases were already reported as pathogenic variant in clinical database DECIPHER. Microarray also detected many LOH (all autosomal, >3.0 mb size) that covered genes with spermatogenesis related function. The mechanism of action of LOH in pathogenesis of SCOS still remains unravelled. CNVs and LOH related to spermatogenesis identified from two different sample types (blood vs. testicular tissue) were discordant. This study should be extended for larger cohort of patients.

Karyotype analysis of amniotic fluid cells and report of chromosomal abnormalities in 15,401 cases of Iranian women

The aim of present study was to assess the karyotypes of amniotic fluid cells and find the frequency of chromosomal abnormalities and their significance in clinical setting. A total of 15,401 pregnant women were assessed from March 2016 to May 2019, and 14,968 amniotic fluid samples were successfully cultured. These fetuses were grouped according to different indications including advanced maternal age, abnormal nuchal translucency (NT) values, positive first/second trimester screening results, high risk NIPT results, very low PAPP-A and free β-hCG multiples of the normal median (MoM) results, abnormal ultrasound findings or previous history of chromosomal abnormalities. Results indicated the presence of normal karyotype in 90.2% (13,497/14,968) of fetuses. Totally, 46.4% (6945/14,968) of fetuses were 46,XX and 43.8% (6552/14,968) had 46,XY chromosome pattern. A total of 1077 abnormal karyotypes were found among 14,968 fetuses, thus the rate of abnormal fetuses was calculated to be 7.2% (1072/14,968). Meanwhile, a total of 394 cases (2.8%) had a normal polymorphism in their karyotype. In other words, abnormal karyotypes were detected in one of 13.9 cases of patients underwent amniocentesis. Down syndrome, Edward’s syndrome, abnormal mosaicisms and Patau’s syndrome were detected in 4.4% (659/14,968), 0.57% (85/14,968), 0.49% (74/14,968) and 0.24% (36/14,968) of cases, respectively. Sex chromosomal abnormalities including Klinefelter syndrome, Turner syndrome and 47,XXX karyotype were detected in 64 cases (0.43%). In this article, the rates of chromosomal abnormalities are compared between different groups of patients based on the advanced maternal age, abnormal NT values, very low PAPP-A and free β-hCG MoMs results, and positive FTS results. The current investigation provides insight into the most appropriate indications for amniocentesis in Iran.

Cell-free fetal DNA testing and its correlation with prenatal indications

BackgroundThe prenatal test of cell-free fetal DNA (cffDNA) is also known as noninvasive prenatal testing (NIPT) with high sensitivity and specificity. This study is to evaluate the performance of NIPT and its clinical relevance with various clinical indications.MethodsA retrospective analysis was conducted on 14,316 pregnant women with prenatal indications, including advanced maternal age (≥35 years), maternal serum screening abnormalities, the thickened nuchal translucency (≥2.5 mm) and other ultrasound abnormalities, twin pregnancy/IVF-ET pregnancy, etc. The whole-genome sequencing (WGS) of maternal plasma cffDNA was employed in this study.ResultsA total of 189 (1.32%) positive NIPT cases were identified, and 113/189 (59.79%)cases were confirmed by invasive prenatal testing. Abnormal serological screening (53.14%) was the most common indication, followed by elderly pregnancy (23.02%). The positive prediction value for T21, T18, T13, sex chromosome abnormalities, other autosomal aneuploidy abnormalities, and CNV abnormalities were 91.84, 68.75,37.50, 66.67, 14.29, and 6.45%, respectively. The positive rate and the true positive rate of nuchal translucency (NT) thickening were the highest (4.17 and 3.33%), followed by the voluntary requirement group (3.49 and 1.90%) in the various prenatal screening indications. The cffDNA concentration was linearly correlated with gestational age (≥10 weeks) and the positive NIPT group’s Z-score values.Conclusionswhole-genome sequencing of cffDNA has extremely high sensitivity and specificity for T21, high sensitivity for T18, sex chromosome abnormalities, and T13. It also provides evidence for other abnormal chromosomal karyotypes (CNV and non-21/18/13 autosomal aneuploidy abnormalities). The cffDNA concentration is closely related to the gestational age and determines the specificity of NIPT. Our results highlight NIPT’s clinical significance, which is an effective prenatal screening tool for high-quality care of pregnancy.

Efficiency of Noninvasive Prenatal Testing for Sex Chromosome Aneuploidies

Objective: This study was designed to investigate the efficiency of noninvasive prenatal testing (NIPT) for screening fetal sex chromosome aneuploidies (SCAs) through sequencing of cell-free DNA in maternal plasma. Methods: This is a retrospective study on the positive NIPT results for SCAs collected from our hospital between January 2012 and December 2018. Samples with positive NIPT results for SCAs were then confirmed by prenatal or postnatal karyotyping analysis. Results: After cytogenetic analysis, abnormal karyotypes were confirmed in 104 cases and the overall positive predictive value (PPV) of NIPT for SCAs was 43.40% (102/235). The most frequently detected karyotypes included 47,XXY (n = 42), 47,XXX (n = 20), 47,XYY (n = 16), and 45,X (n = 2). Meanwhile, 10 cases were confirmed with mosaic karyotype 45,X/46,XX and 14 cases with numerical or structural chromosome abnormalities, including a double trisomy 48,XXX,+18. Cytogenetic results from the other 131 cases showed normal XX or XY, which were discordant with NIPT results. Upon analysis of parental karyotypes, 29 (12.34%) showed false positivity in NIPT results that were caused by maternal sex chromosome abnormalities. Conclusion: NIPT is an effective screening tool for SCA with a PPV of 43.40%. Maternal karyotype abnormalities occurred in 12.34% of the cases with abnormal NIPT. Diagnostic testing of the fetus and the mother are recommended.

P–736 Elevated levels of ambient air pollutants increase the primary sex ratio in human embryos

Abstract Study question Are there any associations between ambient outdoor air pollution and the primary sex ratio (PSR)? Summary answer Short-term exposure to increased PM10, PM2.5 and NO2 levels were significantly associated with higher PSR. What is known already PSR estimates represent a backward extrapolation from data based on spontaneous or induced abortions, fetal deaths or live births and are usually male-biased. A recent study, analyzing 3- to 6-day-old embryos derived from assisted reproductive technology (ART) procedures, showed that the sex ratio at conception is unbiased (0.5). Epidemiologic studies of air pollution on secondary (birth) sex ratio showed that higher levels of particulate pollution were associated with increased rates of female birth. However, a direct association between urban levels of air pollutants and PSR has not been reported. Study design, size, duration A retrospective cohort study was carried out to assess the impact of long- or short-term exposure to six ambient outdoor air pollutants (particulate matter, PM10µm and PM2.5µm; SO2; CO; NO2; O3) on PSR (XY/XX) of couples undergoing their first IVF cycle for preimplantation genetic screening (N = 337). Data was from fixed air quality monitoring stations across the city between January 2014 and December 2018. Embryos with sex chromosome abnormalities were excluded from the analysis. Participants/materials, setting, methods Average concentrations of the pollutants for the 90 (long-term exposure) and 15 days (short-term exposure) predating oocyte retrieval represented the exposures of interest. Pollutant levels were categorized into quartiles (Q1 to Q4) and exposure risk was divided into two periods in which average concentrations and confidence intervals for the pollutants were in the upper quartile (Q4 period) or not (Q1-Q3 period). The strength association between exposure risk and PSR was performed through analysis of covariance. Main results and the role of chance The estimated means of PM10, PM2.5, SO2, NO2, O3 and CO for Q1-Q3/Q4 periods were 27.7/39.3, 16.7/23.7, 2.5/3.9, 37.0/46.4, 32.2/45.3 µg/m3 and 0.64/0.87 ppm and 26.3/43.0, 16.0/26.3, 2.4/4.2, 36.5/47.8, 31.7/50.4 µg/m3 and 0.62/0.90 ppm for long- and short-term exposures, respectively. PM10, PM2.5 and NO2 levels in the Q4 period had significantly higher PSR (138.1, 134.0 and 137.6) when compared to Q1-Q3 period (94.4, 98.1 and 96.4) for the short-term exposure (p = 0.0193; p = 0.0439; p = 0.0180, respectively). PM10, PM2.5, SO2, NO2 and CO levels in the Q4 and Q1-Q3 periods for the long-term exposure showed no significant effect on PSR. Contrastingly, O3 levels in the Q4 period had significantly lower PSR (82.6) when compared to Q1-Q3 (115.9) for the long-term exposure (p = 0.0202). A monotonic increase in PSR was observed with increased PM10 concentration in the Q4 period for the short-term exposure (F-ratio: 4.4476; p = 0.0352). Limitations, reasons for caution Some limitations of the study should be underlined, such as its retrospective nature, exposure assessment based on pollutant levels derived from a network average across city sites, and limited extrapolation of the results to the general population. Wider implications of the findings: Our data suggest that short-term exposure to environmental factors could affect the primary sex ratio in polluted seasons or cities. A monotonic effect on PSR in the case of exposure to increasing PM10 levels was identified. Trial registration number Not applicable

P-736 Elevated levels of ambient air pollutants increase the primary sex ratio in human embryos

Abstract Study question Are there any associations between ambient outdoor air pollution and the primary sex ratio (PSR)? Summary answer Short-term exposure to increased PM10, PM2.5 and NO2 levels were significantly associated with higher PSR. What is known already PSR estimates represent a backward extrapolation from data based on spontaneous or induced abortions, fetal deaths or live births and are usually male-biased. A recent study, analyzing 3- to 6-day-old embryos derived from assisted reproductive technology (ART) procedures, showed that the sex ratio at conception is unbiased (0.5). Epidemiologic studies of air pollution on secondary (birth) sex ratio showed that higher levels of particulate pollution were associated with increased rates of female birth. However, a direct association between urban levels of air pollutants and PSR has not been reported. Study design, size, duration A retrospective cohort study was carried out to assess the impact of long- or short-term exposure to six ambient outdoor air pollutants (particulate matter, PM10µm and PM2.5µm; SO2; CO; NO2; O3) on PSR (XY/XX) of couples undergoing their first IVF cycle for preimplantation genetic screening (N = 337). Data was from fixed air quality monitoring stations across the city between January 2014 and December 2018. Embryos with sex chromosome abnormalities were excluded from the analysis. Participants/materials, setting, methods Average concentrations of the pollutants for the 90 (long-term exposure) and 15 days (short-term exposure) predating oocyte retrieval represented the exposures of interest. Pollutant levels were categorized into quartiles (Q1 to Q4) and exposure risk was divided into two periods in which average concentrations and confidence intervals for the pollutants were in the upper quartile (Q4 period) or not (Q1-Q3 period). The strength association between exposure risk and PSR was performed through analysis of covariance. Main results and the role of chance The estimated means of PM10, PM2.5, SO2, NO2, O3 and CO for Q1-Q3/Q4 periods were 27.7/39.3, 16.7/23.7, 2.5/3.9, 37.0/46.4, 32.2/45.3 µg/m3 and 0.64/0.87 ppm and 26.3/43.0, 16.0/26.3, 2.4/4.2, 36.5/47.8, 31.7/50.4 µg/m3 and 0.62/0.90 ppm for long- and short-term exposures, respectively. PM10, PM2.5 and NO2 levels in the Q4 period had significantly higher PSR (138.1, 134.0 and 137.6) when compared to Q1-Q3 period (94.4, 98.1 and 96.4) for the short-term exposure (p = 0.0193; p = 0.0439; p = 0.0180, respectively). PM10, PM2.5, SO2, NO2 and CO levels in the Q4 and Q1-Q3 periods for the long-term exposure showed no significant effect on PSR. Contrastingly, O3 levels in the Q4 period had significantly lower PSR (82.6) when compared to Q1-Q3 (115.9) for the long-term exposure (p = 0.0202). A monotonic increase in PSR was observed with increased PM10 concentration in the Q4 period for the short-term exposure (F-ratio: 4.4476; p = 0.0352). Limitations, reasons for caution Some limitations of the study should be underlined, such as its retrospective nature, exposure assessment based on pollutant levels derived from a network average across city sites, and limited extrapolation of the results to the general population. Wider implications of the findings Our data suggest that short-term exposure to environmental factors could affect the primary sex ratio in polluted seasons or cities. A monotonic effect on PSR in the case of exposure to increasing PM10 levels was identified. Trial registration number Not applicable