Clinical impact of additional findings detected by genome-wide non-invasive prenatal testing: Follow-up results of the TRIDENT-2 study.

In the TRIDENT-2 study, all pregnant women in the Netherlands are offered genome-wide non-invasive prenatal testing (GW-NIPT) with a choice of receiving either full screening or screening solely for common trisomies. Previous data showed that GW-NIPT can reliably detect common trisomies in the general obstetric population and that this test can also detect other chromosomal abnormalities (additional findings). However, evidence regarding the clinical impact of screening for additional findings is lacking. Therefore, we present follow-up results of the TRIDENT-2 study to determine this clinical impact based on the laboratory and perinatal outcomes of cases with additional findings. Between April 2017 and April 2019, additional findings were detected in 402/110,739 pregnancies (0.36%). For 358 cases, the origin was proven to be either fetal (n = 79; 22.1%), (assumed) confined placental mosaicism (CPM) (n = 189; 52.8%), or maternal (n = 90; 25.1%). For the remaining 44 (10.9%), the origin of the aberration could not be determined. Most fetal chromosomal aberrations were pathogenic and associated with severe clinical phenotypes (61/79; 77.2%). For CPM cases, occurrence of pre-eclampsia (8.5% [16/189] vs 0.5% [754/159,924]; RR 18.5), and birth weight <2.3rd percentile (13.6% [24/177] vs 2.5% [3,892/155,491]; RR 5.5) were significantly increased compared to the general obstetric population. Of the 90 maternal findings, 12 (13.3%) were malignancies and 32 (35.6%) (mosaic) pathogenic copy number variants, mostly associated with mild or no clinical phenotypes. Data from this large cohort study provide crucial information for deciding if and how to implement GW-NIPT in screening programs. Additionally, these data can inform the challenging interpretation, counseling, and follow-up of additional findings.

Noninvasive Prenatal Test Results Indicative of Maternal Malignancies: A Nationwide Genetic and Clinical Follow-Up Study.

PURPOSE: Noninvasive prenatal testing (NIPT) for fetal aneuploidy screening using cell-free DNA derived from maternal plasma can incidentally raise suspicion for cancer. Diagnostic routing after malignancy suspicious-NIPT faces many challenges. Here, we detail malignancy suspicious-NIPT cases, and describe the clinical characteristics, chromosomal aberrations, and diagnostic routing of the patients with a confirmed malignancy. Clinical lessons can be learned from our experience. METHODS: Patients with NIPT results indicative of a malignancy referred for tumor screening between April 2017 and April 2020 were retrospectively included from a Dutch nationwide NIPT implementation study, TRIDENT-2. NIPT profiles from patients with confirmed malignancies were reviewed, and the pattern of chromosomal aberrations related to tumor type was analyzed. We evaluated the diagnostic contribution of clinical and genetic examinations. RESULTS: Malignancy suspicious-NIPT results were reported in 0.03% after genome-wide NIPT, and malignancies confirmed in 16 patients (16/48, 33.3%). Multiple chromosomal aberrations were seen in 23 of 48 patients with genome-wide NIPT, and a malignancy was confirmed in 16 patients (16/23, 69.6%). After targeted NIPT, 0.005% malignancy suspicious-NIPT results were reported, in 2/3 patients a malignancy was confirmed. Different tumor types and stages were diagnosed, predominantly hematologic malignancies (12/18). NIPT data showed recurrent gains and losses in primary mediastinal B-cell lymphomas and classic Hodgkin lymphomas. Magnetic resonance imaging and computed tomography were most informative in diagnosing the malignancy. CONCLUSION: In 231,896 pregnant women, a low percentage (0.02%) of NIPT results were assessed as indicative of a maternal malignancy. However, when multiple chromosomal aberrations were found, the risk of a confirmed malignancy was considerably high. Referral for extensive oncologic examination is recommended, and may be guided by tumor-specific hallmarks in the NIPT profile.

A prospective study on rapid exome sequencing as a diagnostic test for multiple congenital anomalies on fetal ultrasound.

OBJECTIVE: Conventional genetic tests (quantitative fluorescent-PCR [QF-PCR] and single nucleotide polymorphism-array) only diagnose ~40% of fetuses showing ultrasound abnormalities. Rapid exome sequencing (rES) may improve this diagnostic yield, but includes challenges such as uncertainties in fetal phenotyping, variant interpretation, incidental unsolicited findings, and rapid turnaround times. In this study, we implemented rES in prenatal care to increase diagnostic yield. METHODS: We prospectively studied 55 fetuses. Inclusion criteria were: (a) two or more independent major fetal anomalies, (b) hydrops fetalis or bilateral renal cysts alone, or (c) one major fetal anomaly and a first-degree relative with the same anomaly. In addition to conventional genetic tests, we performed trio rES analysis using a custom virtual gene panel of ~3850 Online Mendelian Inheritance in Man (OMIM) genes. RESULTS: We established a genetic rES-based diagnosis in 8 out of 23 fetuses (35%) without QF-PCR or array abnormalities. Diagnoses included MIRAGE (SAMD9), Zellweger (PEX1), Walker-Warburg (POMGNT1), Noonan (PTNP11), Kabuki (KMT2D), and CHARGE (CHD7) syndrome and two cases of Osteogenesis Imperfecta type 2 (COL1A1). In six cases, rES diagnosis aided perinatal management. The median turnaround time was 14 (range 8-20) days. CONCLUSION: Implementing rES as a routine test in the prenatal setting is challenging but technically feasible, with a promising diagnostic yield and significant clinical relevance.

The impact of national prenatal screening on the time of diagnosis and outcome of pregnancies affected with common trisomies, a cohort study in the Northern Netherlands.

BACKGROUND: To evaluate the impact of the introduction of prenatal screening on time of detection and pregnancy outcome for trisomy 21 (T21), trisomy 18 (T18) and trisomy 13 (T13). METHODS: We performed a retrospective, population-based cohort study in the Northern Netherlands including 503 trisomy cases born between 2005 and 2012. Screening tests and invasive procedures, timing of diagnosis and pregnancy outcome were compared between the period before (2005-2006) and after introduction (2007-2012) using X 2 tests. RESULTS: There was an increase in proportion of women who had a prenatal screening and/or invasive test, from 62% in 2005-2006 to 84% in 2010-2012 (p < 0.01), while the proportion of prenatally diagnosed cases did not change (60% overall). In women < =35 years 47% of the cases were diagnosed prenatally vs 73% in women >35 years (p < 0.01). More T13/T18 cases were diagnosed <24 weeks after introduction (62% vs 84%; p < 0.01). In T13/T18 intra-uterine death decreased (26% vs 15%), while terminations increased: 55% vs 72%. CONCLUSION: The introduction of prenatal screening had limited impact on the time of detection and outcome of the most common trisomies. The introduction of the 20-week anomaly scan has resulted in more trisomy cases diagnosed <24 weeks and a shift from fetal death to terminations.

Outcome of infants presenting with echogenic bowel in the second trimester of pregnancy.

OBJECTIVE: Fetal echogenic bowel (FEB) is a soft marker found on second trimester sonography. Our main aim was to determine the outcome of infants who presented with FEB and secondarily to identify additional sonographic findings that might have clinical relevance for the prognosis. DESIGN: We reviewed all pregnancies in which the diagnosis FEB was made in our Fetal Medicine Unit during 2009-2010 (N=121). We divided all cases into five groups according to additional sonographic findings. Group 1 consisted of cases of isolated FEB, group 2 of FEB associated with dilated bowels, group 3 of FEB with one or two other soft markers, group 4 of FEB with major congenital anomalies or three or more other soft markers, and group 5 consisted of FEB with isolated intrauterine growth restriction (IUGR). RESULTS: Of 121 cases, five were lost to follow-up. Of the remaining 116 cases, 48 (41.4%) were assigned to group 1, 15 (12.9%) to group 2, 15 (12.9%) to group 3, 27 (23.2%) to group 4, and 11 (9.5%) to group 5. The outcome for group 1 was uneventful. In group 2 and 3, two anomalies, anorectal malformation and cystic fibrosis, were detected postnatally (6.7%). In group 4, mortality and morbidity were high (78% resp. 22%). Group 5 also had high mortality (82%) and major morbidity (18%). CONCLUSIONS: If FEB occurs in isolation, it is a benign condition carrying a favourable prognosis. If multiple additional anomalies or early IUGR are observed, the prognosis tends to be less favourable to extremely poor.

Jejunoileal atresia and cystic fibrosis: don't miss it.

BACKGROUND: While an increased prevalence of cystic fibrosis (CF) in patients with jejunal atresia and ileal atresia (JIA) has been described previously, it still may not be a practice routine to indicate a sweat test or DNA test for CFTR mutations in newborns presenting with JIA. Leading textbooks do not mention JIA as a possible presenting clinical feature of CF. We describe two cases of JIA with a delayed diagnosis of CF (4 months [post mortem] and 19 months). This led to a retrospective review of all patients with JIA in our hospital. We hypothesised that also in the past although indicated further testing for CF had not always been performed. METHODS: Over an 18-year period from January 1991 until December 2008, all cases of JIA in our centre were reviewed (n=50). We compared patients who have been tested for CF (n=18) with patients who have not been tested for CF (n=32), with respect to their patient characteristics, either by logistic regression analysis or a nonparametric test (p<0.05). RESULTS: Of all 50 patients the proportion of infants actually tested for CF was 18 (36%). A statistical significant difference between the group of patients who were tested for CF versus the group of those who were not tested was found in a higher occurrence of postoperative bilious retention after 7 days (56% versus 25%, respectively), and postoperative complications (78% versus 34%, respectively). CF was confirmed in 4 (8%). CONCLUSION: Testing for CF in newborns presenting with JIA does not appear to be common practice. A timely diagnosis of CF leads to presymptomatic treatment and has beneficial effects on morbidity and mortality. CF should be tested for in all children with JIA. We recommend a sweat test for term children and CFTR DNA testing as a first step for preterm infants. Medical professional awareness may be increased if future editions of leading text books in the relevant fields should include JIA as an indication to follow an appropriate CF-diagnostic algorithm. TRIAL REGISTRATION: Statement on reporting of a clinical trial: This article is not based on a clinical trial.

Quality aspects of prenatal cytogenetic diagnosis: determining the effect of various factors involved in handling amniotic fluid and chorionic villus material for cytogenetic diagnosis.

OBJECTIVES: To investigate the effect of factors involved in cell culturing and slide preparation of amniotic fluid (AF) and chorionic villus biopsies (CVB) for prenatal cytogenetic diagnosis. METHODS: The effect on the outcome of our standard AF cell culture procedure of volume and appearance of the submitted AF specimen, gynaecologist performing the amniocentesis, week of gestation in which the specimen was taken and culture medium was retrospectively investigated. In a prospective study controlled experimental variation was introduced in composition of fixative, relative humidity, temperature and airflow during slide preparation from primary CVB and AF in situ cultures. For evaluation, analysis of regression or variance was used. RESULTS: Provided that at least 0.8 mL AF per culture dish was admitted, none of the investigated factors appeared as critical resulting in unacceptable variation in outcome. Variation in appearance of the AF had a relatively major impact: bloody or brown AF resulted in a 3 days longer culture time. To a limited degree, metaphase quality of AF and CVB cells was affected by composition of fixative, relative humidity, ambient temperature and airflow during slide preparation. CONCLUSION: Current prenatal cytogenetic practice as described here appears in general to be robust and reliable. The investigated conditions are not critical within the investigated range. Expensive measures for fine control of these conditions are, therefore, not required.

Personal experiences of cystic fibrosis (CF) carrier couples prospectively identified in CF families.

This qualitative study explores the experiences of cystic fibrosis (CF) carrier couples, prospectively identified in CF families, and the impact of the resulting genetic risk on reproductive behavior. Of the 12 couples identified until 1997, seven couples participated in semistructured interviews and two couples filled in a questionnaire, two to eight years after receipt of the test-results. After receiving the results, most couples reported that they were shocked, because they did not expect to both be carriers. More anxiety was expressed by those who were pregnant (n = 4) at the time of testing. There were reported difficulties in disclosing the results to family members, and the reactions of family members were not always supportive. After testing, some couples had problems with reproductive decision-making. All viable pregnancies (17 in 8 couples) were monitored by prenatal diagnosis; all affected pregnancies were terminated (6 in 4 couples). Couples who have live-born children after testing may subsequently have concerns during infancy about the correctness of the results of prenatal diagnosis and how to inform their children. Most couples did not regret the testing and, in general, the counseling was experienced positively, although some dissatisfaction was reported with regard to the psychological support received during pregnancy. Couples supported the idea of carrier screening in the general population, although various concerns were expressed. The results indicate a preference for testing before pregnancy. These findings may be useful in investigating possible dilemmas caused by the introduction of population carrier screening. Observations reported here might also apply to other recessively inherited disorders.