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.

The effects of an online decision aid to support the reproductive decision-making process of genetically at risk couples-A pilot study.

Couples at risk of transmitting a genetic disease to their offspring may experience doubts about their reproductive options. This study examines the effects of an online decision aid (DA) on the (joint) reproductive decision-making process of couples (not pregnant at time of inclusion) at risk of transmitting a genetic disease to their offspring. The primary outcome is decisional conflict, and secondary outcomes are knowledge, realistic expectations, deliberation, joint informed decision-making, and decisional self-efficacy. These outcomes were measured with a pretest-posttest design: before use (T0), after use (T1), and 2 weeks after use (T2) of the decision aid (DA). Usability of the DA was assessed at T1. Paired sample t-tests were used to compute differences between baseline and subsequent measurements. The comparisons of T0-T1 and T0-T2 indicate a significant reduction in mean decisional conflict scores with stronger effects for participants with high baseline decisional conflict scores. Furthermore, use of the DA led to increased knowledge, improved realistic expectations, and increased levels of deliberation, with higher increase in participants with low baseline scores. Decision self-efficacy only improved for participants with lower baseline scores. Participants indicated that the information in the DA was comprehensible and clearly organized. These first results indicate that this online DA is an appropriate tool to support couples at risk of transmitting a genetic disease and a desire to have (a) child(ren) in their reproductive decision-making process.

TRIDENT-2: National Implementation of Genome-wide Non-invasive Prenatal Testing as a First-Tier Screening Test in the Netherlands.

The Netherlands launched a nationwide implementation study on non-invasive prenatal testing (NIPT) as a first-tier test offered to all pregnant women. This started on April 1, 2017 as the TRIDENT-2 study, licensed by the Dutch Ministry of Health. In the first year, NIPT was performed in 73,239 pregnancies (42% of all pregnancies), 7,239 (4%) chose first-trimester combined testing, and 54% did not participate. The number of trisomies 21 (239, 0.33%), 18 (49, 0.07%), and 13 (55, 0.08%) found in this study is comparable to earlier studies, but the Positive Predictive Values (PPV)-96% for trisomy 21, 98% for trisomy 18, and 53% for trisomy 13-were higher than expected. Findings other than trisomy 21, 18, or 13 were reported on request of the pregnant women; 78% of women chose to have these reported. The number of additional findings was 207 (0.36%); these included other trisomies (101, 0.18%, PPV 6%, many of the remaining 94% of cases are likely confined placental mosaics and possibly clinically significant), structural chromosomal aberrations (95, 0.16%, PPV 32%,) and complex abnormal profiles indicative of maternal malignancies (11, 0.02%, PPV 64%). The implementation of genome-wide NIPT is under debate because the benefits of detecting other fetal chromosomal aberrations must be balanced against the risks of discordant positives, parental anxiety, and a potential increase in (invasive) diagnostic procedures. Our first-year data, including clinical data and laboratory follow-up data, will fuel this debate. Furthermore, we describe how NIPT can successfully be embedded into a national screening program with a single chain for prenatal care including counseling, testing, and follow-up.

Fetal akinesia deformation sequence, arthrogryposis multiplex congenita, and bilateral clubfeet: Is motor assessment of additional value for in utero diagnosis? A 10-year cohort study.

OBJECTIVE: The diagnosis of fetal akinesia deformation sequence (FADS) is a challenge. Motor assessment is of additional value to advanced ultrasound examinations (AUE) for in utero FADS diagnosis before 24 weeks of gestation. METHODS: All consecutive fetuses with greater than or equal to two contractures on the 20 week structural anomaly scan (2007-2016) were included. Findings at AUE, including motor assessment were analysed and related to outcome. RESULTS: Sixty-six fetuses fulfilled the inclusion criteria. On the basis of the first AUE, FADS was suspected in 13 of 66, arthrogryposis multiplex congenita (AMC) in 12 of 66, bilateral pes equinovares (BPEV) in 40 of 66, and Holt-Oram syndrome in one of 66. On the basis of the first motor assessment, the suspected diagnosis changed in 19 of 66, in 13 of 66 worsening to FADS, six of 66 amelioration from FADS, and confirmed FADS in seven of 13. The result was 20 FADS, seven AMC, and 38 BPEV. Second AUE in 44 fetuses showed additional contractures in two of eight FADS, and one intrauterine fetal death (IUFD). The second motor assessment changed the diagnosis in three of 43, one worsening from BPEV into FADS, two ameliorations from FADS, and confirmed FADS in seven by deterioration of motility. The result was nine FADS, six AMC, and 29 BPEV. CONCLUSION: The results suggest that motor assessment has additional value to distinguish between FADS, AMC, and BPEV.

Origin and clinical relevance of chromosomal aberrations other than the common trisomies detected by genome-wide NIPS: results of the TRIDENT study.

PurposeNoninvasive prenatal screening (NIPS) using cell-free DNA in maternal blood is highly sensitive for detecting fetal trisomies 21, 18, and 13. Using a genome-wide approach, other chromosome anomalies can also be detected. We report on the origin, frequency, and clinical significance of these other chromosome aberrations found in pregnancies at risk for trisomy 21, 18, or 13.MethodsWhole-genome shallow massively parallel sequencing was used and all autosomes were analyzed.ResultsIn 78 of 2,527 cases (3.1%) NIPS was indicative of trisomy 21, 18, or 13, and in 41 (1.6%) of other chromosome aberrations. The latter were of fetal (n = 10), placental (n = 22), maternal (n = 1) or unknown (n = 7). One case lacked cytogenetic follow-up. Nine of the 10 fetal cases were associated with an abnormal phenotype. Thirteen of the 22 (59%) placental aberrations were associated with fetal congenital anomalies and/or poor fetal growth (

Fetal akinesia deformation sequence and massive perivillous fibrin deposition resulting in fetal death in six fetuses from one consanguineous couple, including literature review.

BACKGROUND: Massive perivillous fibrin deposition (MPFD) is associated with adverse pregnancy outcomes and is mainly caused by maternal factors with limited involvement of fetal or genetic causes. We present one consanguineous couple with six fetuses developing Fetal Akinesia Deformation Sequence (FADS) and MPFD, with a possible underlying genetic cause. This prompted a literature review on prevalence of FADS and MPFD. METHODS: Fetal ultrasound examination, motor assessment, genetic testing, postmortem examination, and placenta histology are presented (2009-2019). Literature was reviewed for the association between congenital anomalies and MPFD. RESULTS: All six fetuses developed normally during the first trimester. Thereafter, growth restriction, persistent flexed position, abnormal motility, and contractures in 4/6, consistent with FADS occurred. All placentas showed histologically confirmed MPFD. Genetic analyses in the five available cases showed homozygosity for two variants of unknown significance in two genes, VARS1 (OMIM*192150) and ABCF1 (OMIM*603429). Both parents are heterozygous for these variants. From 63/1999 manuscripts, 403 fetal outcomes were mobilized. In 14/403 fetuses, congenital abnormalities in association with MPFD were seen of which two fetuses with contractures/FADS facial anomalies. CONCLUSION: The low prevalence of fetal contractures/FADS facial anomalies in association with MPFD in the literature review supports the possible fetal or genetic contribution causing FADS and MPFD in our family. This study with literature review supports the finding that fetal, fetoplacental, and/or genetic components may play a role in causing a part of MPFDs.

Rare novel variants in the ZIC3 gene cause X-linked heterotaxy.

Variants in the ZIC3 gene are rare, but have demonstrated their profound clinical significance in X-linked heterotaxy, affecting in particular male patients with abnormal arrangement of thoracic and visceral organs. Several reports have shown relevance of ZIC3 gene variants in both familial and sporadic cases and with a predominance of mutations detected in zinc-finger domains. No studies so far have assessed the functional consequences of ZIC3 variants in an in vivo model organism. A study population of 348 patients collected over more than 10 years with a large variety of congenital heart disease including heterotaxy was screened for variants in the ZIC3 gene. Functional effects of three variants were assessed both in vitro and in vivo in the zebrafish. We identified six novel pathogenic variants (1,7%), all in either male patients with heterotaxy (n=5) or a female patient with multiple male deaths due to heterotaxy in the family (n=1). All variants were located within the zinc-finger domains or leading to a truncation before these domains. Truncating variants showed abnormal trafficking of mutated ZIC3 proteins, whereas the missense variant showed normal trafficking. Overexpression of wild-type and mutated ZIC protein in zebrafish showed full non-functionality of the two frame-shift variants and partial activity of the missense variant compared with wild-type, further underscoring the pathogenic character of these variants. Concluding, we greatly expanded the number of causative variants in ZIC3 and delineated the functional effects of three variants using in vitro and in vivo model systems.

Mutations in ISPD cause Walker-Warburg syndrome and defective glycosylation of α-dystroglycan.

Walker-Warburg syndrome (WWS) is an autosomal recessive multisystem disorder characterized by complex eye and brain abnormalities with congenital muscular dystrophy (CMD) and aberrant a-dystroglycan glycosylation. Here we report mutations in the ISPD gene (encoding isoprenoid synthase domain containing) as the second most common cause of WWS. Bacterial IspD is a nucleotidyl transferase belonging to a large glycosyltransferase family, but the role of the orthologous protein in chordates is obscure to date, as this phylum does not have the corresponding non-mevalonate isoprenoid biosynthesis pathway. Knockdown of ispd in zebrafish recapitulates the human WWS phenotype with hydrocephalus, reduced eye size, muscle degeneration and hypoglycosylated a-dystroglycan. These results implicate ISPD in a-dystroglycan glycosylation in maintaining sarcolemma integrity in vertebrates.

The unfolding clinical spectrum of holoprosencephaly due to mutations in SHH, ZIC2, SIX3 and TGIF genes.

Holoprosencephaly is a severe malformation of the brain characterized by abnormal formation and separation of the developing central nervous system. The prevalence is 1:250 during early embryogenesis, the live-born prevalence is 1:16 000. The etiology of HPE is extremely heterogeneous and can be teratogenic or genetic. We screened four known HPE genes in a Dutch cohort of 86 non-syndromic HPE index cases, including 53 family members. We detected 21 mutations (24.4%), 3 in SHH, 9 in ZIC2 and 9 in SIX3. Eight mutations involved amino-acid substitutions, 7 ins/del mutations, 1 frame-shift, 3 identical poly-alanine tract expansions and 2 gene deletions. Pathogenicity of mutations was presumed based on de novo character, predicted non-functionality of mutated proteins, segregation of mutations with affected family-members or combinations of these features. Two mutations were reported previously. SNP array confirmed detected deletions; one spanning the ZIC2/ZIC5 genes (approx. 100 kb) the other a 1.45 Mb deletion including SIX2/SIX3 genes. The mutation percentage (24%) is comparable with previous reports, but we detected significantly less mutations in SHH: 3.5 vs 10.7% (P=0.043) and significantly more in SIX3: 10.5 vs 4.3% (P=0.018). For TGIF1 and ZIC2 mutation the rate was in conformity with earlier reports. About half of the mutations were de novo, one was a germ line mosaic. The familial mutations displayed extensive heterogeneity in clinical manifestation. Of seven familial index patients only two parental carriers showed minor HPE signs, five were completely asymptomatic. Therefore, each novel mutation should be considered as a risk factor for clinically manifest HPE, with the caveat of reduced clinical penetrance.

CRTAP mutations in lethal and severe osteogenesis imperfecta: the importance of combining biochemical and molecular genetic analysis.

Autosomal recessive lethal and severe osteogenesis imperfecta (OI) is caused by the deficiency of cartilage-associated protein (CRTAP) and prolyl-3-hydroxylase 1 (P3H1) because of CRTAP and LEPRE1 mutations. We analyzed five families in which 10 individuals had a clinical diagnosis of lethal and severe OI with an overmodification of collagen type I on biochemical testing and without a mutation in the collagen type I genes. CRTAP mutations not described earlier were identified in the affected individuals. Although it seems that one important feature of autosomal recessive OI due to CRTAP mutations is the higher consistency of radiological features with OI type II-B/III, differentiation between autosomal dominant and autosomal recessive OI on the basis of clinical, radiological and biochemical investigations proves difficult in the affected individuals reported here. These observations confirm that once a clinical diagnosis of OI has been made in an affected individual, biochemical testing for overmodification of collagen type I should always be combined with molecular genetic analysis of the collagen type I genes. If no mutations in the collagen type I genes are found, additional molecular genetic analysis of the CRTAP and LEPRE1 genes should follow. This approach will allow proper identification of the genetic cause of lethal or severe OI, which is important in providing prenatal diagnosis, preimplantation genetic diagnosis and estimating recurrence risk.