Common Autosomal Aneuploidies Research Articles

A rapid PCR-free next-generation sequencing method for comprehensive diagnosis of chromosome disease syndromes in prenatal samples.

The aim of this study is to investigate the application performance of rapid copy number variation sequencing (rCNV-seq) technology for the detection of chromosomal abnormalities during prenatal diagnosis. Samples were collected from 424 pregnant women who were at high-risk for noninvasive prenatal screening in Kunming Maternal and Child Care Hospital from January 2018 to May 2022. rCNV-seq technique was used to detect fetal chromosome abnormalities and compare the results with that of chromosomal karyotype analysis. The Result showed that 330 (77.83%, 330/424) cases indicated chromosomal abnormalities among 424 high-risk pregnant women who underwent rCNV-seq. Moreover, 94 (22.17%, 94/424) cases were discovered to have copy number variations. Among the 330 fetuses with chromosomal abnormalities, common autosomal aneuploidy was observed in 203 cases (47.87%, 203/424) and sex chromosome aneuploidy was observed in 91 cases (21.46%, 91/424). Moreover, the abnormalities in multiple chromosomes were discovered in 33 cases (7.78%, 33/424), and the rare autosomal aneuploidy was observed in 3 cases (0.71%, 3/424). There were 63 fetuses (14.86%, 63/424) with pathogenic CNVs among the 94 fetuses with variable copy numbers. Of the 245 pregnant women who voluntarily selected G-band karyotyping, 1 fetus with copy number variation had normal karyotype results, and the remaining women were consistent with rCNV-seq. Our study revealed that rCNV-seq has higher accuracy in detecting common trisomy and can also detect chromosomal microdeletions or microduplications that cannot be detected by G-banding karyotype analysis. There is no effective treatment for chromosomal diseases, so it is particularly important to prevent chromosomal diseases through genetic counseling and prenatal diagnosis of chromosomal diseases.

Non-invasive prenatal testing: a revolutionary journey in prenatal testing.

Non-invasive prenatal testing (NIPT) is a pioneering technique that has consistently advanced the field of prenatal testing to detect genetic abnormalities and conditions with the aim of decreasing the incidence and prevalence of inherited conditions. NIPT remains a method of choice for common autosomal aneuploidies, mostly trisomy 21, and several monogenic disorders. The advancements in gene sequencing techniques have expanded the panel of conditions where NIPT could be offered. However, basic research on the impact of several genetic conditions lags behind the methods of detection of these sequence aberrations, and the impact of the expansion of NIPT should be carefully considered based on its utility. With interest from commercial diagnostics and a lack of regulatory oversight, there remains a need for careful validation of the predictive values of different tests offered. NIPT comes with many challenges, including ethical and economic issues. The scientific evidence, technical feasibility, and clinical benefit of NIPT need to be carefully investigated before new tests and developments are translated into clinical practice. Moreover, the implementation of panel expansion of NIPT should accompany expert genetic counseling pre- and post-testing.

Risk factors in the origin of Down syndrome

Down syndrome (DS) is the most common autosomal aneuploidy and the leading cause of intellectual disability of genetic origin worldwide. It is identified as a syndrome in which the variability of its clinical manifestations and the severity of its phenotype have a multifactorial origin. Worldwide prevalence ranges between 1 per 700 live births and several factors that may be involved in the origin of DS have been proposed. Our objective was to describe updates regarding risk factors in the cytogenetic origin or cause of DS. We conducted a narrative review study in which a literature search was carried out from January to June 2022 in databases such as PubMed, EBSCO, Medigraphic, ClinicalKey, and meta-search engines such as Elsevier and Evidence Alerts. Only articles published in the last 10 years in English and Spanish were included. The search terms used were: Down syndrome, risk factors, prevention. Although DS is a very common chromosomal pathology worldwide, there is no single risk factor at the origin of meiotic or mitotic nondisjunction of chromosome 21, but rather each of the associated risk factors contributes to a greater or lesser degree to a cytogenetic predisposition in the etiology of trisomy 21. During the review it was identified that the main established risk factor associated with DS is still advanced maternal age (≥ 35 years).

Cell-free DNA Screening for Aneuploidy.

Cell-free DNA (cfDNA) screening has high detection for the common fetal autosomal aneuploidies, but is not diagnostic. The positive predictive value should be utilized in counseling after a positive cell-free DNA screen, and diagnostic testing should be offered for confirmation. cfDNA screening does not report a result in ~3% of cases; nonreportable results indicate an increased risk for aneuploidy and some adverse perinatal outcomes. False-positive cfDNA screening occurs due to confined placental mosaicism, maternal copy number variants, mosaicism, and cancer. Pretest education and counseling should be provided with emphasis on the potential benefits, risks, and limitations before cfDNA screening.

Non-invasive prenatal testing (NIPT) in twin pregnancies affected by early single fetal demise: A systematic review of NIPT and vanishing twins.

The screening performance of non-invasive prenatal testing (NIPT) in vanishing twin (VT) pregnancies is relatively unknown. To close this knowledge gap, we conducted a systematic review of the available literature. Studies describing the test performance of NIPT for trisomy 21, 18, 13, sex chromosomes and additional findings in pregnancies with a VT were retrieved from a literature search with a publication date until October 4, 2022. The methodological quality of the studies was assessed with the quality assessment tool for diagnostic accuracy studies-2 (QUADAS-2). The screen positive rate of the pooled data and the pooled positive predictive value (PPV) were calculated using a random effects model. Seven studies, with cohort sizes ranging from 5 to 767, were included. The screen positive rate of the pooled data for trisomy 21 was 35/1592 (2.2%), with a PPV of 20% (confirmation in 7/35 cases [95% CI 9.8%-36%]). For trisomy 18, the screen positive rate was 13/1592 (0.91%) and the pooled PPV 25% [95% CI 1.3%-90%]. The screen positive rate for trisomy 13 was 7/1592 (0.44%) and confirmed in 0/7 cases (pooled PPV 0% [95% CI 0%-100%]). The screen positive rate for additional findings was 23/767 (2.9%), of which none could be confirmed. No discordant negative results were reported. There is insufficient data to fully evaluate NIPT performance in pregnancies with a VT. However, existing studies suggest that NIPT can successfully detect common autosomal aneuploidies in pregnancies affected by a VT but with a higher false positive rate. Further studies are needed to determine the optimal timing of NIPT in VT pregnancies.

Prenatal diagnosis with chromosome microarray analysis and pregnancy outcomes of fetuses with umbilical cord cysts

Objective To investigate the prenatal diagnostic value of chromosome microarray analysis (CMA) in fetuses with isolated or non-isolated umbilical cord cysts (UCCs) of various locations and numbers. Methods Between November 2015 and November 2021, 45 pregnant women carrying fetuses with UCCs underwent amniocentesis and CMA. Fetal prognoses were followed from 6 months to 5 years. Results Five cases (11.1%, 5/45) of chromosomal aberrations were detected. No significant difference in total chromosome abnormalities was found between fetuses with isolated and non-isolated UCCs (13.3% [2/15] vs 10% [3/30]; p > .999). No common autosomal aneuploidies were found in fetuses with isolated UCCs. At follow-up, among 45 fetuses, there were 11 (24.4%) pregnancy terminations, 26 (57.8%) live healthy births, 4 (8.9%) postnatal UCC-related surgeries, and 4 (8.9%) live births of fetuses with other diseases. The frequency of postnatal surgeries of the infants with UCCs located adjacent to the anterior abdominal wall was higher than those located adjacent to the fetal surface of the placenta (30.8% [4/13] vs 0% [0/22]; p = .014). All 26 live healthy neonates and 4 neonates that underwent postnatal surgery had an overall good prognosis. Conclusions For fetuses with isolated or non-isolated UCC, CMA could be a choice for parents after providing detailed information. Even when surgery was required, pregnancy outcomes and short- and long-term prognoses for fetuses with UCCs were favorable.

RUNX1 Upregulation Causes Mitochondrial Dysfunction via Regulating the PI3K-Akt Pathway in iPSC from Patients with Down Syndrome.

Down syndrome (DS) is the most common autosomal aneuploidy caused by trisomy of chromosome 21. Previous studies demonstrated that DS affected mitochondrial functions, which may be associated with the abnormal development of the nervous system in patients with DS. Runt-related transcription factor 1 (RUNX1) is an encoding gene located on chromosome 21. It has been reported that RUNX1 may affect cell apoptosis via the mitochondrial pathway. The present study investigated whether RUNX1 plays a critical role in mitochondrial dysfunction in DS and explored the mechanism by which RUNX1 affects mitochondrial functions. Expression of RUNX1 was detected in induced pluripotent stem cells of patients with DS (DS-iPSCs) and normal iPSCs (N-iPSCs), and the mitochondrial functions were investigated in the current study. Subsequently, RUNX1 was overexpressed in N-iPSCs and inhibited in DS-iPSCs. The mitochondrial functions were investigated thoroughly, including reactive oxygen species levels, mitochondrial membrane potential, ATP content and lysosomal activity. Finally, RNA-sequencing was used to explore the global expression pattern. It was observed that the expression levels of RUNX1 in DS-iPSCs were significantly higher than those in normal controls. Impaired mitochondrial functions were observed in DS-iPSCs. Of note, overexpression of RUNX1 in N-iPSCs resulted in mitochondrial dysfunction, while inhibition of RUNX1 expression could improve the mitochondrial function in DS-iPSCs. Global gene expression analysis indicated that overexpression of RUNX1 may promote the induction of apoptosis in DS-iPSCs by activating the PI3K/Akt signaling pathway. The present findings indicate that abnormal expression of RUNX1 may play a critical role in mitochondrial dysfunction in DS-iPSCs.

Cytogenetic outcomes following a failed cell-free DNA screen: a population-based retrospective cohort study of 35,146 singleton pregnancies

Cell-free fetal DNA screening is routinely offered to pregnant individuals to screen for aneuploidies. Although cell-free DNA screening is consistently more accurate than multiple-marker screening, it sometimes fails to yield a result. These test failures and their clinical implications are poorly described in the literature. Some studies suggest that a failed cell-free DNA screening result is associated with increased likelihood of cytogenetic abnormalities. This study aimed to assess the association between a failed cell-free DNA test and common aneuploidies. The objectives were to determine: (1) the proportion of test failures on first and subsequent attempts, and (2) whether a failed cell-free DNA screen on first attempt is associated with increased likelihood of common aneuploidies (trisomies 21, 18, and 13, and sex chromosome aneuploidies). This was a population-based retrospective cohort study using data from Ontario's prescribed maternal and child registry, Better Outcomes Registry and Network Ontario. The study included all singleton pregnancies in Ontario with an estimated date of delivery from September 1, 2016 to March 31, 2019 that had a cell-free DNA screening record in the registry. Specific outcomes (trisomies 21, 18, and 13, and sex chromosome aneuploidies) of pregnancies with a failed cell-free DNA screen on first attempt were compared with those of pregnancies with low-risk cell-free DNA-screening results using modified Poisson regression adjusted for funding status (publicly funded vs self-paid), gestational age at screening, method of conception, and maternal age for autosomal aneuploidies. Our cohort included 35,146 pregnancies that had cell-free DNA screening during the study period. The overall cell-free DNA screening failure rate was 4.8% on first attempt and 2.2% after multiple attempts. An abnormal cytogenetic result for trisomies 21, 18, and 13, or sex chromosome aneuploidies was identified in 19.4% of pregnancies with a failed cell-free DNA screening for which cytogenetic testing was performed. Pregnancies with a failed cell-free DNA screen on first attempt had a relative risk of 130.3 (95% confidence interval, 64.7-262.6) for trisomy 21, trisomy 18, or trisomy 13, and a risk difference of 5.4% (95% confidence interval, 2.6-8.3), compared with pregnancies with a low-risk result. The risk of sex chromosome aneuploidies was not significantly greater in pregnancies with a failed result compared with pregnancies with a low-risk result (relative risk, 2.7; 95% confidence interval, 0.9-7.9; relative difference, 1.2%; 95% confidence interval,-0.9 to 3.2). Cell-free DNA screening test failures are relatively common. Although repeated testing improves the likelihood of an informative result, pregnancies with a failed cell-free DNA screen upon first attempt remain at increased risk for common autosomal aneuploidies, but not sex chromosome aneuploidies.

EP450: Effectiveness and utility of noninvasive prenatal screening (NIPS) for sex chromosome aneuploidies

Noninvasive prenatal screening (NIPS) has high sensitivity and specificity for the common autosomal aneuploidies. However, compared to these autosomal trisomies, the few studies assessing NIPS for detecting sex chromosome aneuploidy (SCA) have shown higher false positive rates; particularly for monosomy X. The primary goal of this study was to determine the effectiveness and utility of NIPS as a tool for recognizing SCA; we also discuss uptake of diagnostic testing. Over 39 months (August 2018-October 2021), we performed NIPS for 1438 specimens. Overall, the proportion of specimens with any high-risk result was 2.6% (37/1438). Of those, autosomal aneuploidy was prognosticated in 2.09% (30/1438), while SCA was suspected in 0.49% (7/1438) of patients, with similar frequencies of abnormal results being published among other laboratories performing this test. Of the seven pregnancies at high risk for SCA, three were high risk for Turner syndrome (45,X); three for Klinefelter syndrome (47,XXY); and one for Triple X (47,XXX). None of the patients with high-risk results for SCA elected to have additional prenatal diagnostic testing. Also, no patients elected to terminate pregnancies based on NIPS SCA results. Follow-up karyotype analysis was available for four of these seven cases: three newborns and one product of conception (POC) specimen. Of the three pregnancies at high risk for monosomy X, two resulted in miscarriage; with one having follow-up genetic testing that confirmed monosomy X (true positive). The third high-risk monosomy X case resulted in a liveborn. Subsequent testing of the newborn including FISH, karyotype and microarray yielded results consistent with a normal female complement (false positive). Of the three pregnancies at high risk for 47,XXY, all resulted in live births, with two confirmed as true positives in the newborns (the third did not pursue testing). The case at high risk for 47,XXX was reported as phenotypically normal but no diagnostic testing was performed. Seven patients received high-risk results for SCA; however, none elected to pursue diagnostic testing prenatally via amniocentesis or CVS. Follow-up testing was available in four of the seven cases. Three were true positive (two 47,XXY and one 45,X) and one was a false positive (45,X). Calculation of the test specifications (sensitivity, specificity, PPV, NPV) for SCAs is limited due to lack of confirmatory genetic testing and limited phenotypes observed in the newborn period (and beyond) for some conditions. NIPS allows for earlier diagnosis of SCA, which could aid in behavioral interventions or fertility concerns/management for people with SCAs.

Analysis of transcription factors in accessible open chromatin in the 18-trisomy syndrome based on single cell ATAC sequencing technique.

Trisomy 18 syndrome is one of the most common autosomal aneuploidy disorders. Little is known about the genetic regulation leading to the clinical phenotypes associated with the occurrence and development of trisomy 18 syndrome disorders (e.g., mental retardation, cardiac and renal abnormalities). To explore the regulatory factors that influence the phenotypes of the disease, this study used single-cell ATAC sequencing to analyze transcription factors in the accessibility chromatin regions of the single-nucleus cells of the cord blood from 18-trisomy syndrome and control subjects. A single-cell library constructed by capturing 11,611 cells identified seven major immune cell populations, and the results of cell number statistics suggested the presence of abnormalities in the immune system of 18-trisomy syndrome patients. Fourteen transcription factors (P<0.05, |FC|>1.2) were identified by analyzed accessibility chromatin regions. The relative expression levels of four of these transcription factors (TEAD1, TEAD2, TEAD4, Twist2) were confirmed using real-time quantitative fluorescence PCR. In conjunction with information from the literature, this study suggests that these four transcription factors may be associated with abnormalities in cardiac and skeletal development in patients with the 18-trisomy syndrome, thereby providing candidate molecules for mechanistic studies on the occurrence and development of the 18-trisomy syndrome phenotypes.

Performance of non-invasive prenatal screening for sex chromosome aneuploidies and parental decision-making.

Performance of non-invasive prenatal screening for sex chromosome aneuploidies and parental decision-making.

Certified Nurse-Midwives' Experiences With Provision of Prenatal Genetic Screening: A Case for Interprofessional Collaboration.

Prenatal genetic screening (GS) for the most common autosomal aneuploidies encompasses maternal serum screening (MSS) and noninvasive prenatal testing (NIPT, or cell-free fetal DNA testing). In the United States, most maternity care is provided by obstetrician-gynecologists; however, women are increasingly utilizing the services of certified nurse-midwives (CNMs). Currently, limited research exists on midwives' experiences with providing prenatal GS. Therefore, the purpose of this study was to explore CNMs' experiences in providing prenatal GS. A semistructured guide focused on MSS and NIPT was used to interview a convenience sample of 13 CNMs. Results were coded and analyzed using grounded theory to elicit overarching themes. Results were organized into 6 themes describing CNMs' prenatal GS provision: (1) clinical protocols; (2) patient education; (3) patient-CNM shared decision-making process; (4) testing initiation; (5) results delivery; and (6) follow-up coordination. Key influences on midwives' perspectives on offering prenatal GS included a noninterventionist approach to pregnancy and past experiences with false-positive MSS results. Participants had an understanding of prenatal GS that was appropriate to midwifery scope of practice. Results indicate that NIPT utilization is compatible with the midwifery philosophy of noninterventionism, although midwives had limited experiences with NIPT to date.

An efficient method for noninvasive prenatal diagnosis of fetal trisomy 13, trisomy 18, and trisomy 21.

BackgroundMolecular size determination of circulating free fetal DNA in maternal plasma is an important detection method for noninvasive prenatal testing (NIPT). The fetal DNA molecule is the primary factor determining the overall performance of NIPT and its clinical interpretation. The proportion of cell-free fetal DNA molecules is expressed as the fetal DNA fraction in the plasma of pregnant women.MethodsWe proposed an effective method to deduce fetal chromosomal aneuploidy based on the proportion of a certain range of DNA fragment lengths from maternal plasma. We gradually narrowed the range of the upper and lower boundary via a traversing algorithm.ResultsWe explored the optimal range of the upper and lower boundary by using size-based DNA fragment length. Using this range, the accuracy of the sensitivity and specificity could be improved by up to 100% for detecting the three most common autosomal aneuploidies, namely trisomy 13, trisomy 18, trisomy 21 in the sample set.ConclusionsNumerical experiments demonstrate that our method is effective and efficient. The program is available upon request.

Update in non-invasive prenatal testing.

Non-invasive prenatal testing (NIPT) has revolutionized the approach to prenatal diagnosis and, to date, it is the most superior screening method for the common autosomal aneuploidies, mostly trisomy 21. This screening is having a significant population-wide impact on the uptake of conventional screening and diagnostic testing. In recent years, emerging genomic technologies, largely based around next generation sequencing, have expanded the analyses to the sub-chromosomal aneuploidies. However, further clinical validation studies are needed to better characterize this technology. These tests bring advantage through providing a higher diagnostic yield, without risks of miscarriage than previously available diagnostic test, but also raise the question of harms related to an increase in uncertain and unknown results. In view of the revolution brought about by the NIPT, numerous scientific societies have published recommendations regarding the appropriate application of cell-free DNA screening in pregnancy. In this review, we discuss the progress that has been made to date in NIPT.

Perinatal outcomes following cell-free DNA screening in >32000 women: Clinical follow-up data from a single tertiary center.

Cell-free DNA (cfDNA) screening for aneuploidy was clinically introduced in 2011. We aim to focus on the follow-up information from a single tertiary center undergoing genome-wide cfDNA screening to evaluate this technology. A total of 32431 cases were retrospectively reviewed. The screening was performed using a BGI protocol, and the cfDNA results were analyzed together with the pregnancy outcomes, confirmatory testing results, and ultrasound findings. Of the 32431 cfDNA screening cases, successful follow-up was conducted in 287 (82.2%) cases with high-risk cfDNA results, 85 (94.4%) cases with copy number variation (CNV) and rare autosomal trisomy (RAT) results, and 26060 (81.5%) cases with low-risk cfDNA results. Among them, 234 with high-risk cfDNA results chose invasive testing, revealing 169 true positive cases. In cases with CNV and RAT results, 45 cases underwent invasive diagnosis, revealing six pathogenic CNVs and three uniparental disomies. In cases with low-risk cfDNA results, three false negative cases were confirmed. Cell-free DNA screening appears to be effective in detecting the common autosomal aneuploidies, but one-third of our cohort with high-risk results rejected confirmatory testing. Our data provide information on the clinical experience of large-scale whole-genome cfDNA screening that has global relevance for the implementation of this technology.

Genetic Counselors' Perspectives About Cell-Free DNA: Experiences, Challenges, and Expectations for Obstetricians.

The expansion of cell-free fetal DNA (cfDNA) screening for a larger and diverse set of genetic variants, in addition for use among the low-risk obstetric population, presents important clinical challenges for all healthcare providers involved in the delivery of prenatal care. It is unclear how to leverage the different members of the healthcare team to respond to these challenges. We conducted interviews with 25 prenatal genetic counselors to understand their experience with the continued expansion of cfDNA screening. Participants supported the use of cfDNA screening for the common autosomal aneuploidies, but noted some reservations for its use to identify fetal sex and microdeletions. Participants reported several barriers to ensuring that patients have the information and support to make informed decisions about using cfDNA to screen for these different conditions. This was seen as a dual-sided problem, and necessitated additional education interventions that addressed patients seeking cfDNA screening, and obstetricians who introduce the concepts of genetic risk and cfDNA to patients. In addition, participants noted that they have a professional responsibility to educate obstetricians about cfDNA so they can be prepared to be gatekeepers of counseling and education about this screening option for use among the general obstetric population.

A Paradigm Shift: Considerations in Prenatal Cell-Free DNA Screening.

Testing to determine the health of a fetus has undergone multiple iterations since the widespread adoption of amniocentesis in the 1970s, including several combinations of ultrasound and/or maternal serum screening. The clinical paradigm for prenatal screening for fetal chromosome aneuploidies was transformed by the introduction of cell-free DNA (cfDNA) screening or noninvasive prenatal screening in 2011. The clinical performance of cfDNA screening is well-established for the most common autosomal and sex chromosome aneuploidies with a detection rate exceeding 90% for all aneuploidies. One of the most significant advantages of cfDNA screening relative to maternal serum screening is the markedly reduced false-positive rate, which is <0.5%. The clinical implementation of cfDNA screening is discussed at length, including key biological, preanalytical, and analytical factors that affect test performance. cfDNA prenatal screening for whole chromosome aneuploidies has become routine in high-risk obstetric populations. There is tremendous interest in expanding cfDNA screening to the general obstetric population. Early studies suggest that routine application of cfDNA screening is both feasible and effective, although significant economic and quality control considerations remain.

Sex chromosome aneuploidy screened by non-invasive prenatal testing from 35 827 singletons: prenatal diagnosis and pregnancy determinations

Objective To assess the positive predictive value (PPV) of fetal sex chromosome aneuploidy (SCA) identified by non-invasive prenatal testing (NIPT) and investigate families' acceptance of SCA fetus. Methods All suspected SCA cases screened by NIPT from singletons were reviewed in Prenatal Diagnosis Center of Shanghai First Maternity and Infant Hospital from April 1, 2015 to October 31, 2017. Maternal age, NIPT indications, prenatal diagnosis protocols, testing results and their pregnancy determinations were analyzed. Results NIPT was provided to 35 827 singletons and 86 suspected SCA cases were identified out of 35 823 successful ones, giving a positive detection rate of 0.24%. The average maternal age was (31.5±5.0) years. After genetic counseling, 20 patients declined prenatal diagnosis, the rest 66 cases proceeded with aminiocentesis and fetal chromosomal testing, of which 32 were cytogenetically diagnosed as SCA with the PPV of 48.5% . The SCA fetus consisted of 25 sex chromosome trisomies (seven cases of 47,XXX, three cases of 47,XYY and 15 cases of 47,XXY), one monosomy X (45,X), three mosacisms (47,XXY/48,XXYY, 47,XXX/45,X, 45,X/46,XX, one for each) and three microdeletions/microduplications. Besides, two false positive NIPT cases were proved to be low level of maternal mosacism (45,X/46,XX, 5% and 10% for each). After genetic counseling, 17 out of 20 who declined prenatal diagnosis and 9 out of 32 who diagnosed fetal SCAs continued their pregnancies, with a combined proportion of continued pregnancy of 50%. Thirty-four pregnancies were also continued after exclusion of SCA. Interestingly, the proportion of continued pregnancy among those sex chromosomal trisomy fetuses was only 32%(8/25). Conclusions As a safe and rapid prenatal testing for common autosomal aneuploidies, NIPT could also identify some types of SCA, but with relatively low PPV. More long-term researches are required to determine its sensitivity and specificity. For some types of SCA with mild phenotypes, some family would continue the pregnancy. Therefore, limitations of NIPT should be appropriately explained during both pre- and post-testing counseling. Key words: Non-invasive prenatal testing; Sex chromosome aberrations; Prenatal diagnosis; Aneuploidy; Chimera; Predictive value of tests

Prenatal and Postnatal Follow-up in Trisomies 13 and 18: A 20-Year Experience in a Tertiary Center.

Trisomies 13 and 18 are among the most common autosomal aneuploidies associated with high mortality rates. Conventional management strategies offer to limit interventional support; however, some of the recent studies suggest that intervention does make a difference in terms of survival. A retrospective cohort study was performed between January 1996 and January 2016, covering all cases with such trisomies. A total of 69 cases were reviewed for clinical aspects, outcome, and management strategies. In almost all pregnancies with follow-up, at least one indication present for invasive testing (54/55). Invasive testing was not performed in 18.5% of such cases. All parents opted for termination in cases with prenatal diagnosis. None of the liveborns had prenatal diagnoses, thus, neonatal resuscitation and intensive care unit admission were not withheld in such infants. Major intervention was done in only one patient with full trisomy 13. Median survival for infants with full trisomies 13 and 18 was 36 and 60 days, respectively. Almost half the patients died within 1 month. To which extent the major interventions should be withheld is an issue of debate in managing such infants; however, current approaches are subject to change, given the technological advances.

Expanded indications for noninvasive prenatal genetic testing: Implications for the individual and the public

Summary Objectives Noninvasive prenatal testing (NIPT) has rapidly been integrated into the routine management of women at increased risk for common autosomal aneuploidies. Advances in molecular diagnostics have quickly made it possible to use NIPT to screen for other genetic variants not formerly included in routine prenatal genetic screening or diagnostic testing, including sex chromosome aneuploidies (SCAs) and microdeletion syndromes. Moreover, it is anticipated that NIPT will become available for use by the low-risk obstetric population in the near future as test performance becomes better defined with clinical experience. The pace and trajectory of these advances raise important questions about the clinical, ethical, and public health impact of this new prenatal technology for individual patients, families, and society. Methods A cross-sectional study was conducted of pregnant women who had utilized NIPT to examine key patient-reported aspects of the educational and decision-making process regarding current and forthcoming indications of this screening test. Results A total of 139 participants completed the survey. Two-thirds (n = 90, 65.2%) entered their prenatal care with the intention to undergo prenatal genetic screening or testing primarily because of self-identification as advanced maternal age (AMA); these participants were more likely to have had prenatal genetic assessment in a prior pregnancy (P = 0.016). The remainder proceeded with NIPT following a directed discussion with their clinician about testing options. Leading decision-making factors in favor of NIPT included the absence of iatrogenic risk, the increased accuracy of NIPT as compared to conventional screening to detect trisomy (T) 21, T13, T18, and SCAs, and the ability to determine fetal sex. Participants had greater familiarity with T21, T13, and T18 than with SCAs and overall less familiarity with the microdeletions that NIPT is currently being marketed to detect. While participants recognized the superior accuracy of NIPT over conventional screens, few recognized the different detection and false positive rates within a screening panel for each of the identifiable conditions. Despite their awareness of the increased accuracy of NIPT, 41.3% (n = 57) described the testing process as stressful, 64.7% (n = 90) recommended a formal, written informed consent process in addition to 50.0% (n = 68) genetic counseling prior to screening. Conclusions Pregnant women are less familiar with SCAs, microdeletions, and the capability of NIPT to screen for these variants than they are with T21, T18, and T13. Additionally, despite the increased accuracy and capability of NIPT as compared to conventional screening tests, women reported feeling anxiety during the screening process. The results of this study highlight the need for clinicians and policymakers to provide effective guidance and support for patients’ decision-making about NIPT both at the present time and as the indications expand to include all pregnant populations and detailed fetal genomic analysis.