Screening for trisomies by cfDNA testing of maternal blood in twin pregnancy: update of The Fetal Medicine Foundation results and meta-analysis

OBJECTIVES

To report on the routine clinical implementation of cell-free DNA (cfDNA) analysis of maternal blood for trisomies 21, 18 and 13 in twin pregnancy and to define the performance of the test by combining our results with those identified in a systematic review of the literature.

METHODS

The data for the prospective study were derived from screening for trisomies 21, 18 and 13 in twin pregnancies at 10 + 0 to 14 + 1 weeks' gestation. Two populations were included; first, self-referred women to the Fetal Medicine Centre in London or Brugmann University Hospital in Brussels and, second, women selected for the cfDNA test after routine first-trimester combined testing at one of two National Health Service hospitals in England. This dataset was used to determine the performance of screening for the three trisomies. Search of MEDLINE, EMBASE, CENTRAL (The Cochrane Library), ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform (ICTRP) was carried out to identify all peer-reviewed publications on clinical validation or implementation of maternal cfDNA testing for trisomies 21, 18 and 13 in twin pregnancy. A meta-analysis was then performed using our data and those in the studies identified by the literature search.

RESULTS

In our dataset of 997 twin pregnancies with a cfDNA result and known outcome, the test classified correctly 16 (94.1%) of the 17 cases of trisomy 21, nine (90.0%) of the 10 cases of trisomy 18, one (50.0%) of the two cases of trisomy 13 and 962 (99.4%) of the 968 cases without any of the three trisomies. The literature search identified seven relevant studies, excluding our previous papers because their data are included in the current study. In the combined populations of our study and the seven studies identified by the literature search, there were 56 trisomy-21 and 3718 non-trisomy-21 twin pregnancies; the pooled weighted detection rate (DR) and false-positive rate (FPR) were 98.2% (95% CI, 83.2-99.8%) and 0.05% (95% CI, 0.01-0.26%), respectively. In the combined total of 18 cases of trisomy 18 and 3143 non-trisomy-18 pregnancies, the pooled weighted DR and FPR were 88.9% (95% CI, 64.8-97.2%) and 0.03% (95% CI, 0.00-0.33%), respectively. For trisomy 13, there were only three affected cases and two (66.7%) of these were detected by the cfDNA test at a FPR of 0.19% (5/2569).

CONCLUSIONS

The performance of cfDNA testing for trisomy 21 in twin pregnancy is similar to that reported in singleton pregnancy and is superior to that of the first-trimester combined test or second-trimester biochemical testing. The number of cases of trisomies 18 and 13 is too small for accurate assessment of the predictive performance of the cfDNA test. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Surgical and anesthetic management for hepatectomy in two pediatric patients with trisomy 18, pulmonary hypertension, and hepatoblastoma

Children with trisomy 18 are surviving longer and undergoing more aggressive life-sustaining therapy. This report describes two patients with trisomy 18 and hepatoblastoma (HB) successfully resected in the setting of significant pulmonary hypertension. Forty-four previously published cases of the association between HB and trisomy 18 are reviewed. With careful multidisciplinary preoperative planning, successful resection of HB in children with trisomy 18 who have significant pulmonary hypertension is feasible. Because HB and trisomy 18 are increasing in prevalence, the need for timely liver tumor resection in the setting of pulmonary hypertension will be more common.

The ratio of cavum septi pellucidi width to anteroposterior cerebellar diameter: A novel index as a diagnostic adjunct for prenatal diagnosis of trisomy 18

AIM

To explore the effectiveness of cavum septi pellucidi (CSP) width to anteroposterior cerebellar diameter (APCD) ratio as a diagnostic adjunct for prenatal diagnosis of trisomy 18.

METHODS

Images of normal fetal brain within 15 and 35 weeks were stored in our center from 2016 to 2017. Images of aneuploid fetuses were retrospectively collected from 2004 to 2017. The transverse cerebellar diameter, APCD and CSP width were measured. CSP/APCD and APCD/transverse cerebellar diameter ratios were calculated and compared between euploid and aneuploid fetuses.

RESULTS

One thousand and forty one fetuses were analyzed, including 817 euploid fetuses and 224 aneuploid fetuses (trisomy 21 117 cases, trisomy 18 82 cases, trisomy 13 9 cases, sex-linked 16 cases). No correlation had been found between both ratios and gestational weeks (P > 0.05). In aneuploid groups, means of ratios were both significantly different just between trisomy 18 group and euploid group (P < 0.05). The best area under the curve was shown by the CSP/APCD ratio. The cutoff value of CSP/APCD was 0.46 (sensitivity 87.0%, specificity 85.0%).

CONCLUSION

A wide CSP or cerebellar hypoplasia warrants a more detailed ultrasound screening and genetic counseling. A larger CSP/APCD ratio alerts us to trisomy 18 syndrome, especially in cases with subtle anomalies.

Experiences of children with trisomy 18 referred to pediatric palliative care services on two continents

Children with trisomy 18 that survive beyond the neonatal period have multiple congenital anomalies, neurodevelopmental disability, and high mortality rates. The experience of children with trisomy 18 who receive pediatric palliative care services is largely unknown. We conducted a retrospective review of children with trisomy 18 receiving pediatric palliative care services at both Boston Children's Hospital, USA and Great Ormond Street Hospital, UK from January 1, 2004 to January 1, 2015. Fifty-eight children with trisomy 18 were referred to pediatric palliative care, 38 in the United Kingdom, 20 in the United States. Median age at referral was 19 days (2-89) in the United Kingdom, and 25 days (1-463) in the United States. Median length of time being followed by pediatric palliative care was 32 days (1-1,637) in the United Kingdom and 67 days (3-2,442) in the United States. The only significant difference in the two cohorts (p = .001) was in likelihood of receiving cardiac surgical intervention-37% in the United States, 0% the United Kingdom. Children with trisomy 18 receive pediatric palliative care services, with variable age at referral and for a variable length of time. Further research is needed to understand the experience of children with trisomy 18 and their families receiving pediatric palliative care services.

Employ ductus venous blood flow in the early detection of trisomy 21, trisomy 18, and trisomy 13: A meta-analysis

BACKGROUND AND OBJECTIVE

Ductus venosus (DV) Doppler has been suggested as a biomarker for the early screening of trisomy diseases. However, results from different studies have been largely inconsistent. This study aimed to investigate the relationship between DV and top 3 fetal aneuploidies by a systematical meta-analysis: trisomy 21 (T21), trisomy 18 (T18), and trisomy 13 (T13).

METHODS

We performed a literature search covering articles from Medline, PubMed, RePORTER, and Elsevier publications. DV-T21/T18/T13 relation data were extracted from 9, 7, and 6 previous studies, respectively, including 31,053, 28,092 and 26,721 pregnant women worldwide. Both random-effects and fixed-effect model were used to study the log odds ratio (LOR) of T21, T18, and T13 in case of DV. Four potential influential factors were studied using a multiple linear regression (MLR) model, including maternal age, data age, sample size, and population region.

RESULTS

DV was significantly related to T21, T18, and T13 (LOR = 3.44, 3.89 and 3.46; P value <2.1E-13). Significant between-study variance was observed for T21 (P value <1.71E-14), but not for T18 (P value >.05) and T13 (P value >.87). MLR results suggested that significant influential factors could include population region (P value <.0021), but not sample size, data age, and maternal age (P value >.078).

CONCLUSIONS

Integrating DV could help in the detection of trisomy. However, accuracy and validity may vary depending on the population regions, which need further study.

Routine first-trimester screening for fetal trisomies in twin pregnancy: cell-free DNA test contingent on results from combined test

OBJECTIVE

To report on the routine clinical implementation of cell-free DNA (cfDNA) analysis of maternal blood for trisomies 21, 18 and 13, contingent on the results of the first-trimester combined test in twin pregnancy.

METHODS

Screening for trisomies 21, 18 and 13 was carried out in 959 twin pregnancies by assessment of a combination of maternal age, fetal nuchal translucency thickness, and serum free β-human chorionic gonadotropin and pregnancy-associated plasma protein-A at 11-13 weeks' gestation in two UK NHS hospitals. Women in the high-risk group (risk ≥ 1 in 100) were offered the option of invasive testing, cfDNA testing or no further testing, and those in the intermediate-risk group (risk 1 in 101 to 1 in 2500 in the first phase of the study and 1 in 101 to 1 in 500 in the second phase) were offered cfDNA or no further testing. The trisomic status of the pregnancies was determined by prenatal or postnatal karyotyping or examination of the neonates.

RESULTS

In 42 (4.4%) of the 959 pregnancies, there was termination, miscarriage or stillbirth with no known karyotype or there was loss to follow-up. The 917 pregnancies with known trisomic status of both twins included six that were discordant for trisomy 21, four that were discordant for trisomy 18 and 907 with no trisomy 21, 18 or 13. Following combined screening, 47 (5.1%), 203 (22.1%) and 667 (72.7%) of the pregnancies were classified as high risk, intermediate risk and low risk, respectively. The high-risk group included five (83.3%) cases of trisomy 21 and three (75.0%) of trisomy 18. The cfDNA test was carried out in 224 pregnancies and results were provided in 214 (95.5%); this group included six pregnancies with trisomy 21, three with trisomy 18 and 206 with no trisomy 21, 18 or 13. The cfDNA test classified correctly as screen positive all six cases of trisomy 21 and two of the three with trisomy 18, and as screen negative for each of the trisomies all 206 unaffected pregnancies. Contingent screening led to prenatal detection of all cases of trisomy 21 and three of four with trisomy 18.

CONCLUSION

This study has demonstrated the feasibility of introducing cfDNA testing, contingent on the results of the first-trimester combined test for major trisomies, in a routine population of twin pregnancies. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Prenatal cell-free DNA screening for fetal aneuploidy in pregnant women at average or high risk: Results from a large US clinical laboratory

BACKGROUND

We evaluated the performance of a cell-free DNA (cfDNA) prenatal screening assay for trisomies 21, 18, and 13, and sex chromosome aneuploidies (SCAs) among a population of pregnant women that included both those at average and high risk.

METHODS

Specimen collection, cfDNA extraction, massively parallel sequencing, and bioinformatics analysis were conducted per laboratory protocol. Assay results, concordance with pregnancy outcomes, and performance characteristics were evaluated.

RESULTS

A total 75,658 specimens from 72,176 individual pregnant women were received. Technical reasons accounted for 288 (0.4% of all received samples) tests not performed. In the final analysis cohort (N = 69,794), 13% of pregnancies were considered at average risk and 87% at high risk. Mean gestational age at specimen collection was 15.1 weeks. Of the 69,794 unique pregnancies, 1,359 (1.9%) had positive test results. Among the results with confirmed outcomes, PPV for trisomies 21, 18, and 13 was 98.1%, 88.2%, and 59.3%, respectively; the PPV was 69.0% for SCAs and 75.0% for microdeletions. Overall, PPV was 87.2%, sensitivity was 97.9%, and specificity was 99.9%.

CONCLUSION

This cfDNA prenatal screening assay provides highly accurate discrimination between affected and unaffected pregnancies among a population of pregnant women at average and high risk for fetal genetic abnormalities.

Attitudes of clinicians toward cardiac surgery and trisomy 18

Trisomy 18 is an autosomal trisomy condition characterized by minor to major birth defects, severe disabilities, and high rates of pre- and postnatal mortality. Interventions for these infants have traditionally been withheld with focus instead on palliative support. The issues and attitudes surrounding corrective surgery of congenital heart defects, which is a birth defect that occurs in approximately 90% of infants with trisomy 18, is of our study's interest as recent literature has indicated that cardiac surgery is being performed and may lead to improved survival compared to palliative care. Thus, our study aimed to describe clinician attitudes toward cardiac surgery and trisomy 18. We surveyed 378 clinicians from multiple specialties, including genetic counselors, involved in the pre- and postnatal care of infants with trisomy 18. Descriptive statistics were performed to describe all clinicians' responses, and a secondary analysis with stratifications by clinician type was also performed. Forty-eight percent (n = 378) of clinicians felt it was appropriate to discuss the option of cardiac surgery. Ethical concerns and insufficient outcome data were the most agreed upon reasons for not offering cardiac surgery. Trisomy 18 not being uniformly lethal and expressed parental wishes were the most agreed upon justifications for offering surgery. Clinicians felt the discussion of the option of cardiac surgery is appropriate, however are hesitant due to ethical concerns and insufficient outcome data. Results from this study aim to promote discussion and collaboration among clinicians to improve consistency in patient care.

Early diagnosis of trisomy 21, trisomy 18 and trisomy 13 using nuchal translucency thickness and ductus venosus blood flow waveform in West China

Abnormal nuchal translucency (NT) thickness and ductus venosus (DV) blood flow have been associated with trisomy 21, 18 and 13. However, the association of abnormal DV with these aneuploidies varies among clinical studies. The present study examined the possibility of using NT combined with DV for the early diagnosis of the three aforementioned aneuploidies in the Western Chinese population, focusing on three aspects: Biological pathway analysis, theoretical statistical analysis and clinical data analysis from 1,962 first‑trimester pregnant women from Western China. The pathway and statistical analyses performed suggested the reliability of integrating NT and DV in the prediction of the three aneuploidies. The clinical data analysis suggested that integrating NT and DV, compared with NT alone, resulted in increased predictive power (34.09 vs. 22.45%), better rejection probability (0.21 vs. 0.44%), increased specificity (96.71 vs. 94.07%) and increased sensitivity (89.47 vs. 80.49%). The present results suggested the reliability of integrating NT and DV for the early diagnosis of trisomy 21, 18 and 13 for the Western Chinese population. The present results provided novel statistical analyses to the field of prenatal diagnosis in the Western Chinese population.

The indications for early prenatal diagnosis of trisomy 18: a 7-year experience at mainland China

Objective: To report the experience with first-trimester prenatal detection of pregnancies complicated by trisomy 18.Study design: Proven cases of trisomy 18 identified between 11 and 14 weeks of gestation were retrospectively reviewed. Information on maternal demographics, prenatal sonographic findings, indications for prenatal diagnosis and chromosomal analysis results was obtained by reviewing medical records.Results: During the 7-year period from January 2011 to December 2017, 89 cases of full trisomy 18 had first-trimester indications for prenatal diagnosis at Guangzhou Women and Children's Medical Center. Eighty-five (95.5%) had abnormal sonographic findings in the first trimester. The most common finding was increased nuchal translucency (55.1%), followed by cystic hygroma (18.0%), omphalocele (14.6%), and fetalis hydrops (11.2%). Four cases (4.5%) were not associated with any abnormal first-trimester sonographic finding, and were diagnosed because of routine positive screening results for trisomy 18. A single case was diagnosed because of a positive cell-free DNA (cfDNA) result.Conclusion: These results demonstrate that a large number of fetuses with trisomy 18 have abnormal sonographic findings in the first trimester, and support the continued utility of first-trimester sonographic examination in the diagnosis of this trisomy even with the availability of cfDNA.

Therapeutic experience with hepatoblastoma associated with trisomy 18

Trisomy 18 is often fatal, but patients with this disease can now have longer survival due to proactive treatment intervention. However, hepatoblastomas may develop in these patients. In this study, we report four cases of hepatoblastoma associated with trisomy 18. All of the patients had congenital heart disease and three had undergone intracardiac surgical repair. Tumor growth was relatively slow in all cases, and there were no problems with chemotherapy tolerability and surgical resection. Three of the patients are currently disease-free and the fourth is alive with remaining of the tumor. These cases suggest that combined chemotherapy and surgical resection may be an option to treat hepatoblastoma associated with trisomy 18 when cardiac pulmonary function is relatively stable.

Enhanced First Trimester Aneuploidy Screening with Placental Growth Factor and Alpha Feto-Protein: Detection of Trisomies 18 and 13

OBJECTIVES

To assess the performance of first trimester combined screening (FTS) when enhanced with placental growth factor and alpha feto-protein in the detection of trisomies 18 and 13.

METHODS

A retrospective case-control study. Marker parameters were derived using frozen serum samples. Multivariate Gaussian modelling predicted the detection rate (DR) and false-positive rate (FPR) for trisomies 18 and 13 with FTS and enhanced first trimester screening (eFTS) using the risk of trisomy 21 alone and an additional risk cut-off for trisomy 18, or trisomies 18 or 13.

RESULTS

There were 83 trisomy 18, 22 trisomy 13, and 588 controls. The median placental growth factor levels in trisomies 18 and 13 were 0.75 and 0.65 multiple of the median of controls, respectively (both P < 0.0001). There were no statistically significant differences in alpha feto-protein levels. Modelling predicts that using a trisomy 21 risk cut-off alone, at FPR of 3%, eFTS increases the DR for trisomies 18 and 13 by 0.6-0.8% compared with FTS. Additionally using a trisomy 18 risk cut-off, at an extra FPR of 0.2%, eFTS increased the DR by 0.6-0.9% over FTS; using a trisomy 18 or 13 risk cut-off did not further increase detection for FTS or eFTS. The increase in DR was greater at higher FPR.

CONCLUSION

eFTS increases the detection of trisomies 18 and 13 to a small extent.

Sensitivity of prenatal ultrasound for detection of trisomy 18

Objectives: To evaluate the sensitivity of prenatal ultrasound (US) for trisomy (T18) diagnosis and describe US findings in a large tertiary care institution in the USA. Materials and methods: This was a retrospective cohort of all T18 cases diagnosed at our institution from October 2004 to October 2014 based on prenatal or postnatal genetic diagnostic testing. We included all women with a fetus affected by T18 who had a comprehensive US by a maternal-fetal medicine specialist performed at our institution. US findings were reviewed, classified by organ system, and categorized as an anomaly or soft marker. Chi-square or t-test was used for statistical analysis. Results: We included 128 cases of T18 with confirmed cytogenetic analysis -110 (86%) of which were diagnosed prenatally or suspected by cell-free DNA and confirmed postnatally, and 18 of which underwent neonatal blood sampling alone. One hundred and twenty-one (95%) had at least one abnormal US finding. Anomalies were more frequently identified on US at ≥20 weeks as compared with <20 weeks (93% versus 76%; p = .004). The mean number of findings detected per fetus was 5.1 ± 3.0. Fetuses diagnosed by postnatal sampling alone had a similar number of US exams performed and number of abnormal findings compared to those diagnosed prenatally. Conclusion: Ninety-five percent of fetuses with T18 had at least one abnormal US finding. This sensitivity of is higher than reported in most prior studies, but is not 100%, and should be considered when counseling women regarding prenatal diagnosis of T18. Rationale: Historical detection rates for abnormal sonographic findings in trisomy 18 fetuses range from 70% to 100%. These studies are limited by small sample sizes. This is a contemporary study of ultrasound findings in a large group of women with confirmed trisomy 18 by prenatal or postnatal genetic diagnosis. We provide expansive detail on soft markers and anomalies broken down by organ-system and gestational age.

Spontaneous regression of severe aortic coarctation in trisomy 18

Spontaneous regression of severe aortic coarctation with ductus dependency has not been reported. We experienced a case of trisomy 18 with spontaneous regression of severe aortic coarctation complicated by ventricular septal defect and patent ductus arteriosus. The aortic isthmus diameter was 1.2 mm at birth. After 5 months, it increased to 4.5 mm, and the shape of the isthmus was fully normalised.

Bilateral Wilms'Tumor in Trisomy 18 Syndrome: Case Report and Critical Review of the Literature

We present a patient with trisomy 18 syndrome and bilateral Wilms' tumor representing the second case of the literature. Physicians should remain alert to the possibility of WT in patients with trisomy 18 who may survive beyond infancy. In this event, it may be essential to consider periodic abdominal ultrasound for screening purposes. A critical review of the literature is presented.

Modeling the rare diseases process in dish

For rare diseases, how to mimic the pathological progression is of importance for better understanding the molecular mechanism and identifying potential targets. Induced pluripotent stem cells (iPSCs) technology provides an ideal model to in vitro obtain the diseases-associated cells. In this issue of Intractable & Rare Diseases Research, two birth detect diseases iPS models on phenylketonuria and trisomy 18 were established, and have demonstrated great potential in the research on these rare diseases.

The Diagnosis of Gastric Mucosa-associated Lymphoid Tissue Lymphoma by Flow Cytometry and Fluorescence in situ Hybridization of Biopsy Specimens

Mucosa-associated lymphoid tissue (MALT) lymphoma and reactive inflammatory lymphoid changes are frequently difficult to distinguish based on a routine histological differential diagnosis. We were unable to diagnose gastric MALT lymphoma histologically using specimens obtained by endoscopy, although a flow cytometry (FCM) analysis demonstrated clonality of neoplastic cells by separating cells by CD45 gating. Furthermore, a fluorescence in situ hybridization (FISH) analysis showed trisomy 18. We therefore diagnosed gastric MALT lymphoma with trisomy 18. We recommend that FCM and FISH analyses of biopsy specimens be considered for diagnosing gastric MALT lymphoma if this diagnosis is suspected based on endoscopic findings.

Utility of fetal anteroposterior to transverse cerebellar diameter ratio to exclude cerebellar hypoplasia in trisomy 18

AIM

This study was aimed to determine reference ranges for fetal cerebellar hemisphere biometry, including the transverse cerebellar diameter (TCD), anteroposterior cerebellar diameter (APCD) and APCD/TCD ratio in normal fetuses. In addition, we investigated which parameter would be useful for cerebellar hypoplasia in trisomy 18.

METHODS

This retrospective study included 340 normal singleton pregnancies and 15 cases of trisomy 18, in all of which fetal cerebellar biometry was performed between 14 and 40 weeks of gestational age (GA). The TCD, APCD and APCD/TCD ratio were assessed ultrasonographically.

RESULTS

In normal fetuses, the TCD (r_s = 0.876, P < 0.001) and APCD (r_s = 0.791, P < 0.001) were strongly correlated with GA. However, the APCD/TCD ratio was not correlated with GA (r_s = 0.058, P = 0.289), with median values of 0.52. Low TCD, APCD and APCD/TCD ratio values were detected in 53%, 100% and 100% of trisomy 18 cases, respectively. The median APCD/TCD ratio for trisomy 18 was 0.39 (range, 0.30-0.43), which was significantly lower than that of normal fetuses (P < 0.001). A cut-off APCD/TCD ratio of 0.44 served as a good predictor for trisomy 18 (sensitivity 100%, specificity 95.3% and negative predictive value 100%).

CONCLUSION

This study shows that TCD and APCD are correlated with GA, while the APCD/TCD ratio is a fixed value throughout gestation. Using the APCD/TCD ratio to assess cerebellar hypoplasia in trisomy 18 is useful because it does not require the individual evaluation of the TCD and APCD.

Positive predictive value estimates for cell-free noninvasive prenatal screening from data of a large referral genetic diagnostic laboratory

BACKGROUND

Since its debut in 2011, cell-free fetal DNA screening has undergone rapid expansion with respect to both utilization and coverage. However, conclusive data regarding the clinical validity and utility of this screening tool, both for the originally included common autosomal and sex-chromosomal aneuploidies as well as the more recently added chromosomal microdeletion syndromes, have lagged behind. Thus, there is a continued need to educate clinicians and patients about the current benefits and limitations of this screening tool to inform pre- and posttest counseling, pre/perinatal decision making, and medical risk assessment/management.

OBJECTIVE

The objective of this study was to determine the positive predictive value and false-positive rates for different chromosomal abnormalities identified by cell-free fetal DNA screening using a large data set of diagnostic testing results on invasive samples submitted to the laboratory for confirmatory studies.

STUDY DESIGN

We tested 712 patient samples sent to our laboratory to confirm a cell-free fetal DNA screening result, indicating high risk for a chromosome abnormality. We compiled data from all cases in which the indication for confirmatory testing was a positive cell-free fetal DNA screen, including the common trisomies, sex chromosomal aneuploidies, microdeletion syndromes, and other large genome-wide copy number abnormalities. Testing modalities included fluorescence in situ hybridization, G-banded karyotype, and/or chromosomal microarray analysis performed on chorionic villus samples, amniotic fluid, or postnatally obtained blood samples. Positive predictive values and false-positive rates were calculated from tabulated data.

RESULTS

The positive predictive values for trisomy 13, 18, and 21 were consistent with previous reports at 45%, 76%, and 84%, respectively. For the microdeletion syndrome regions, positive predictive values ranged from 0% for detection of Cri-du-Chat syndrome and Prader-Willi/Angelman syndrome to 14% for 1p36 deletion syndrome and 21% for 22q11.2 deletion syndrome. Detection of sex chromosomal aneuploidies had positive predictive values of 26% for monosomy X, 50% for 47,XXX, and 86% for 47,XXY.

CONCLUSION

The positive predictive values for detection of common autosomal and sex chromosomal aneuploidies by cell-free fetal DNA screening were comparable with other studies. Identification of microdeletions was associated with lower positive predictive values and higher false-positive rates, likely because of the low prevalence of the individual targeted microdeletion syndromes in the general population. Although the obtained positive predictive values compare favorably with those seen in traditional screening approaches for common aneuploidies, they highlight the importance of educating clinicians and patients on the limitations of cell-free fetal DNA screening tests. Improvement of the cell-free fetal DNA screening technology and continued monitoring of its performance after introduction into clinical practice will be important to fully establish its clinical utility. Nonetheless, our data provide valuable information that may aid result interpretation, patient counseling, and clinical decision making/management.

Detection of an Underlying 22q11.2 Duplication in a Female Neonate With Trisomy 18

Current guidelines indicate that in patients with developmental disabilities or congenital anomalies, chromosomal microarray (CMA) is a first-tier diagnostic test. However, for patients with obvious chromosomal syndromes such as trisomy 13, 18, and 21, G-banded karyotyping is still recommended over CMA for establishing a diagnosis. In the case presented herein, a female neonate was suspected of having trisomy 18 based on pre- and postnatal evaluations. Karyotyping was requested but not performed due to insufficient cell growth; Interphase fluorescence in situ hybridization (i-FISH) found an extra copy of chromosome 18. CMA analysis uncovered gain of chromosome 18 and an additional duplication in chromosome 22q11.2, which went undetected with FISH. Our patient died within 40 hours after birth, but it is expected that patients with recognizable chromosomal syndromes could benefit from the discovery of coexisting copy number variations (CNVs) using CMA. This case shows that CMA can be a useful test for patients with recognizable chromosomal syndromes because of the potential benefits for patients and their families when co-existing CNVs are found.

Prenatal diagnosis of inverted duplication deletion 8p syndrome mimicking trisomy 18

Inverted duplication deletion of 8p (invdupdel[8p]) is a well-described and uncommon chromosomal rearrangement. The majority of the reported cases have revealed no life-threatening malformations. Although the invdupdel[8p] syndrome in children with central nervous system abnormalities has been reported before, we present the first prenatal microarray diagnosis of invdupdel[8p] syndrome mimicking trisomy 18 due to similar sonographic features. Contrary to reported cases with invdupdel[8p] syndrome, the present case had severe polyvalvular dysplasia and the infant deceased at day 12 of life. In this case, we also emphasize the diagnostic power of microarray analysis in detecting the underlying genetic causes for fetuses with multiple congenital anomalies. © 2017 Wiley Periodicals, Inc.

Discrepancy between Non-invasive Prenatal Genetic Testing (NIPT) and Amniotic Chromosomal Test due to Placental Mosaicism: A Case Report and Literature Review

We experienced a case of advanced maternal age in which a fetus was found to be positive for trisomy 18 at re-examination following indeterminate non-invasive prenatal genetic testing (NIPT), the amniotic fluid chromosomal test revealed a normal karyotype, and confined placental mosaicism (CPM) was observed in an SNP microarray analysis of the placenta. The child was born with no defects or complications. In the present case, the result of the original NIPT at week 15 of pregnancy was indeterminate and the subsequent re-examination result was positive; since the definitive normal diagnosis was not reported until the latter half of week 21, the pregnant patient was subjected to psychological stress for a long period of time. The problem with NIPT is that most of the fetus-derived cell-free DNA in the maternal blood is not derived directly from the fetus but from the villus cells of the placenta, leading to indefinite diagnoses; for that reason, the pregnant patient was subjected to psychological stress for a long period of time. Of the 18,251 cases undergoing NIPT in the past 2 years in Japan, 51 had indeterminate results; this was the second case in which a subsequent re-examination gave a positive result for trisomy 18.

Analysis of cell-free DNA in maternal blood in screening for aneuploidies: updated meta-analysis

OBJECTIVES

To review clinical validation or implementation studies of maternal blood cell-free (cf) DNA analysis and define the performance of screening for fetal trisomies 21, 18 and 13 and sex chromosome aneuploidies (SCA).

METHODS

Searches of PubMed, EMBASE and The Cochrane Library were performed to identify all peer-reviewed articles on cfDNA testing in screening for aneuploidies between January 2011, when the first such study was published, and 31 December 2016. The inclusion criteria were peer-reviewed study reporting on clinical validation or implementation of maternal cfDNA testing in screening for aneuploidies, in which data on pregnancy outcome were provided for more than 85% of the study population. We excluded case-control studies, proof-of-principle articles and studies in which the laboratory scientists carrying out the tests were aware of fetal karyotype or pregnancy outcome. Pooled detection rates (DRs) and false-positive rates (FPRs) were calculated using bivariate random-effects regression models.

RESULTS

In total, 35 relevant studies were identified and these were used for the meta-analysis on the performance of cfDNA testing in screening for aneuploidies. These studies reported cfDNA results in relation to fetal karyotype from invasive testing or clinical outcome. In the combined total of 1963 cases of trisomy 21 and 223 932 non-trisomy 21 singleton pregnancies, the weighted pooled DR and FPR were 99.7% (95% CI, 99.1-99.9%) and 0.04% (95% CI, 0.02-0.07%), respectively. In a total of 563 cases of trisomy 18 and 222 013 non-trisomy 18 singleton pregnancies, the weighted pooled DR and FPR were 97.9% (95% CI, 94.9-99.1%) and 0.04% (95% CI, 0.03-0.07%), respectively. In a total of 119 cases of trisomy 13 and 212 883 non-trisomy 13 singleton pregnancies, the weighted pooled DR and FPR were 99.0% (95% CI, 65.8-100%) and 0.04% (95% CI, 0.02-0.07%), respectively. In a total of 36 cases of monosomy X and 7676 unaffected singleton pregnancies, the weighted pooled DR and FPR were 95.8% (95% CI, 70.3-99.5%) and 0.14% (95% CI, 0.05-0.38%), respectively. In a combined total of 17 cases of SCA other than monosomy X and 5400 unaffected singleton pregnancies, the weighted pooled DR and FPR were 100% (95% CI, 83.6-100%) and 0.004% (95% CI, 0.0-0.08%), respectively. For twin pregnancies, in a total of 24 cases of trisomy 21 and 1111 non-trisomy 21 cases, the DR was 100% (95% CI, 95.2-100%) and FPR was 0.0% (95% CI, 0.0-0.003%), respectively.

CONCLUSIONS

Screening by analysis of cfDNA in maternal blood in singleton pregnancies could detect > 99% of fetuses with trisomy 21, 98% of trisomy 18 and 99% of trisomy 13 at a combined FPR of 0.13%. The number of reported cases of SCA is too small for accurate assessment of performance of screening. In twin pregnancies, performance of screening for trisomy 21 is encouraging but the number of cases reported is small. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.