Impact of the volume of the myelomeningocele sac on imaging, prenatal neurosurgery and motor outcomes: a retrospective cohort study.

To investigate the association of the myelomeningocele (MMC) volume with prenatal and postnatal motor function (MF) in cases who underwent a prenatal repair. Retrospective cohort study (11/2011 to 03/2019) of 63 patients who underwent a prenatal MMC repair (37 fetoscopic, 26 open-hysterotomy). At referral, measurements of the volume of MMC was performed based on ultrasound scans. A large MMC was defined as greater than the optimal volume threshold (ROC analysis) for the prediction of intact MF at referral (2.7 cc). Prenatal or postnatal intact motor function (S1) was defined as the observation of plantar flexion of the ankle based on ultrasound scan or postnatal examination. 23/63 participants presented a large MMC. Large MMC lesions was associated with an increased risk of having clubfeet by 9.5 times (CI%95[2.1-41.8], p < 0.01), and reduces the chances of having an intact MF at referral by 0.19 times (CI%95[0.1-0.6], p < 0.01). At birth, a large MMC reduces the chance of having an intact MF by 0.09 times (CI%95[0.01-0.49], p < 0.01), and increases the risk of having clubfeet by 3.7 times (CI%95[0.8-18.3], p = 0.11). A lower proportion of intact MF and a higher proportion of clubfeet pre- or postnatally were observed in cases with a large MMC sac who underwent a prenatal repair.Trial registration: Clinicaltrials.gov NCT02230072 and NCT03794011 registered on September 3rd, 2014 and January 4th, 2019.

L1CAM mutations in three fetuses diagnosed by medical exome sequencing.

OBJECTIVE: The L1 cell adhesion molecule (L1CAM) gene, encodes the L1 cell adhesion molecule, is involved in the central nervous system development. Its mutations result in L1 syndrome which is associated with brain malformation and nervous developmental delay. CASE REPORT: We presented three fetuses with hydrocephalus and agenesis of the corpus callosum detected by ultrasound, followed by medical exome sequencing (MES) test with L1CAM mutations: two known missense mutation c.551G > A (p. R184Q) and c.1354G > A (p. G452R), and a novel frameshift mutation c.1322delG which causes the early termination of translation (p. G441Afs∗72). By utilizing multiple computational analysis, all the variants were scored to be likely pathogenic. CONCLUSION: Combined use of ultrasound and MES to identify the molecular etiology of fetal anomalies may contribute to expanding our knowledge of the clinical phenotype of L1 syndrome observed in the south Chinese population.

Prenatal diagnosis of mosaic trisomy 8 by amniocentesis in a fetus with ventriculomegaly and dysgenesis of the corpus callosum.

OBJECTIVE: We present prenatal diagnosis of mosaic trisomy 8 by amniocentesis in a fetus with central nervous system abnormalities. CASE REPORT: A 39-year-old woman was found to have fetal bilateral ventriculomegaly and enlargement of the third ventricle on prenatal ultrasound at 32 weeks of gestation. Fetal magnetic resonance imaging examination confirmed bilateral ventriculomegaly and dysgenesis of the corpus callosum. Amniocentesis was performed subsequently. Array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniotic cells revealed trisomy 8 mosaicism with a result of arr [GRCh37] (8) × 3[0.19], (X,Y) × 1. Conventional cytogenetic analysis on cultured amniocytes showed that among 108 cells in 12 colonies of three cultures, only one cell was abnormal with trisomy 8, trisomy 9 and monosomy 13, while the rest 107 cells had a normal karyotype. Repeat amniocentesis and cord blood sampling revealed a result of arr 8p23.3q24.3 (191,530-146,280,020) × 2.3 with a log2 ratio of 0.2 compatible with 20-30% mosaicism for trisomy 8 on the uncultured amniocytes, and a result of arr 8p23.3q24.3 (191,530-146,280,020) × 2.1 with a log2 ratio of 0.08 compatible with <10% mosaicism for trisomy 8 on the cord blood lymphocytes. Polymorphic DNA marker analysis excluded uniparental disomy 8. A malformed 2440-g dead fetus was delivered at 34 weeks of gestation with facial dysmorphism. CONCLUSION: Cytogenetic discrepancy can occur between cultured and uncultured amniocytes in mosaic trisomy 8 at amniocentesis. aCGH analysis on uncultured amniocytes is useful for confirmation of mosaic trisomy 8 at amniocentesis. Fetuses with low-level mosaicism for trisomy 8 may prenatally present ventriculomegaly and dysgenesis of the corpus callosum.

Regulation of embryonic and adult neurogenesis by Ars2.

Neural development is controlled at multiple levels to orchestrate appropriate choices of cell fate and differentiation. Although more attention has been paid to the roles of neural-restricted factors, broadly expressed factors can have compelling impacts on tissue-specific development. Here, we describe in vivo conditional knockout analyses of murine Ars2, which has mostly been studied as a general RNA-processing factor in yeast and cultured cells. Ars2 protein expression is regulated during neural lineage progression, and is required for embryonic neural stem cell (NSC) proliferation. In addition, Ars2 null NSCs can still transition into post-mitotic neurons, but fail to undergo terminal differentiation. Similarly, adult-specific deletion of Ars2 compromises hippocampal neurogenesis and results in specific behavioral defects. To broaden evidence for Ars2 as a chromatin regulator in neural development, we generated Ars2 ChIP-seq data. Notably, Ars2 preferentially occupies DNA enhancers in NSCs, where it colocalizes broadly with NSC regulator SOX2. Ars2 association with chromatin is markedly reduced following NSC differentiation. Altogether, Ars2 is an essential neural regulator that interacts dynamically with DNA and controls neural lineage development.

Natural History of Ventriculomegaly in Fetal Agenesis of the Corpus Callosum.

OBJECTIVES: To assess the natural evolution of the size of the fetal lateral ventricles throughout pregnancy in fetuses with callosal anomalies. METHODS: Cases of fetal callosal anomalies were retrospectively classified as isolated or complex based on the presence of other structural or genetic anomalies. Longitudinal ultrasound studies were reviewed, and postnatal outcomes were retrieved for isolated cases. RESULTS: In 135 fetuses, those who first presented after 24 weeks' gestation were more likely to have ventriculomegaly (n = 58 of 68 [85%]) than those who presented before 24 weeks (n = 39 of 67 [58%]; P < .001). In 79 cases that had longitudinal follow-up, the mean increase in ventricular width was 0.6 mm/wk, without a significant difference between isolated and complex cases (mean ± SD, 0.6 ± 1.5 versus 0.6 ± 1.1 mm; P = .45). CONCLUSIONS: Callosal anomalies are associated with progressive ventriculomegaly on prenatal ultrasound imaging, without a difference between isolated and complex anomalies. This feature should be considered part of the disease spectrum. The consequence of progressive ventriculomegaly on the long-term neurodevelopmental outcome is still unknown, and further studies should be aimed at obtaining long-term follow-up of these cases.

Evaluation of Hemodynamic Changes in Fetuses With Isolated Mild-to-Moderate Ventriculomegaly by Transabdominal Ultrasound.

OBJECTIVES: To investigate fetal hemodynamic alterations using transabdominal ultrasound in fetuses with isolated mild-to-moderate ventriculomegaly (VM). METHODS: Fetuses diagnosed with isolated mild-to-moderate VM by transabdominal ultrasound were evaluated for hemodynamic changes, including changes in fetal cardiac function, the umbilical artery, the ductus venosus, and the middle cerebral artery. The fetuses with isolated mild-to-moderate VM were divided into 2 groups, namely, before 32 weeks' gestation (20 weeks-31 weeks 6 days) and after 32 weeks' gestation (32-38 weeks), and matched to corresponding healthy control fetuses. RESULTS: The 53 fetuses with VM before 32 weeks had a longer mean isovolumetric relaxation time (IRT; mean ± SD, 42.9 ± 6.8 versus 40.4 ± 5.0 milliseconds; P < .05) and an apparently higher modified myocardial performance index 0.46 ± 0.06 versus 0.43 ± 0.05; P < .01) than the healthy control fetuses. The 43 fetuses with VM after 32 weeks had a significantly longer mean IRT (45.5 ± 6.7 versus 40.9 ± 7.2 milliseconds; P < .01) and a lower UA pulsatility index (0.81 ± 0.13 versus 0.89 ± 0.11; P < .01). The optimal cutoff levels for the IRT in the prediction of adverse perinatal outcomes were 40 and 43 milliseconds before and after 32 weeks, respectively (sensitivity, 100% versus 100%; specificity, 40.4% versus 50.0%; area under the curve, 0.601 versus 0.748; 95% confidence interval, 0.457-0.733 versus 0.590-0.869; P = .291 versus .005). CONCLUSIONS: Some fetuses with isolated mild-to-moderate VM may have impaired cardiac function, characterized by a higher modified myocardial performance index or longer IRT. This finding might be useful for improving fetal surveillance.

Functions of thioredoxin1 in brain development and in response to environmental chemicals in zebrafish embryos.

Thioredoxin is an evolutionarily conserved antioxidant protein that plays a crucial role for fundamental cellular processes and embryonic development. Growing evidence support that Thioredoxin influences cellular response to chemicals insults, particularly those accompanying oxidative stress. The mechanisms underlying the functions of Thioredoxin1 in the embryonic development under the environmental toxicant exposure remain, however, largely unexplored. We report here that thioredoxin1 becomes differentially expressed in zebrafish embryos after exposure to 9 out of 11 environmental chemicals. In situ gene expression analysis show that thioredoxin1 is expressed in neurons, olfactory epithelia, liver and swim bladder under normal conditions. After MeHg exposure, however, thioredoxin1 is ectopically induced in the hair cells of the lateral line and in epithelia cells of the pharynx. Knockdown of Thioredoxin1 induces hydrocephalus and increases cell apoptosis in the brain ventricular epithelia cells. In comparison with 5% malformation in embryos injected with control morpholino, MeHg induces more than 77% defects in Thioredoxin1 knockdown embryos. Our data suggest that there is an association between hydrocephalus and Thioredoxin1 malfunction in embryonic development, and provide valuable information to elucidate the protective role of Thioredoxin1 against chemicals disruption.

Volume growth trend and correlation of atrial diameter with lateral ventricular volume in normal fetus and fetus with ventriculomegaly: A STROBE compliant article.

To explore the growth trend of fetal lateral ventricular volume, for understanding the relationship between atrial diameter (AD) and volume in normal fetus and fetus with ventriculomegaly.Overall, 97 sequential fetal head magnetic resonance imaging scans were performed; these pertained to 50 fetuses with normal lateral ventricles [normal group; gestational age (GA): 24-38 weeks] and 47 fetuses with ventriculomegaly (VM) (VM group; GA: 24-37 weeks). The left, right, and total lateral ventricular volume were measured using 3-dimensional magnetic resonance hydrography (MRH). Correlation coefficient (r) was calculated to assess the relationships of measurements. Lineal regression analysis was used to assess correlation of AD and GA with volume. Between-group differences in terms of AD and volume were assessed using t test.Significant linear growth was observed in the total lateral ventricular volume compared with GA in the normal group with a relative growth rate of 2.87% per week (P <.001). Significant linear relationship between AD and volume was observed, and a significant equation was acquired in the normal group and VM groups, respectively, using the simple linear regression model: left volume = 0.438 * normal left diameter (NLD) + 1.359; right volume = 0.493 * normal right diameter (NRD) + 1.012; left volume = 0.959 * left diameter in VM (VLD) - 2.074; right volume = 0.799 * right diameter in VM (VRD) - 0.443. A significant equation was obtained in the normal group and the VM group, using the multiple linear regression model: Total volume (mL) = 0.396 * NLD + 0.410 * NRD + 3.101; and total volume = 0.989 * VLD + 0.834 * VRD - 3.141, respectively. In terms of AD and volume, the left lateral ventricle was significantly larger than the right side in both groups. The volume of lateral ventricle in AD ≥10 mm group was larger than that in the AD <10 mm group. The total volume in the VM group was significantly larger than that in the normal group.The total lateral ventricular volume increased with GA. AD can be used to evaluate the fetal ventricular volume.

Fetal brain MRI findings and neonatal outcome of common diagnosis at a tertiary care center.

Fetal Magnetic Resonance Imaging (MRI) is increasingly used in prenatal evaluations. OBJECTIVE: Identify common brain malformations on fetal MRI and evaluate perinatal course. METHODS: Fetal consultations from 10/2016 to 12/2017 reviewed. RESULTS: Hundred consultations were requested; 94 were completed. Findings included: posterior fossa malformations (19%), agenesis/dysgenesis of corpus callosum (15%), congenital aqueductal stenosis (CAS) (14%), ventriculomegaly (11%), isolated cortical malformations (8.5%), and holoprosencephaly (6%). Posterior fossa malformations were more likely to be associated with genetic conditions and cardiac malformations. Patients with CAS all required intensive care unit admission. Overall, few patients with congenital brain malformations required feeding or respiratory support at discharge. None had seizures as neonates except two with early epileptic encephalopathy syndromes. CONCLUSIONS: Even though long term neurological prognosis is poor for many conditions including high lifetime risk of epilepsy, most are discharged with no feeding or respiratory support. Seizures are rarely seen in the neonatal period.

Cilia in hereditary cerebral anomalies.

Ciliopathies are complex genetic multi-system disorders causally related to abnormal assembly or function of motile or non-motile cilia. While most human cells possess a non-motile sensory/primary cilium (PC) during development and/or in adult tissues, motile cilia are restricted to specialised cells. As a result, PC-associated ciliopathies are characterised by high phenotypic variability with extensive clinical and genetic overlaps. In the present review, we have focused on cerebral developmental anomalies, which are commonly found in PC-associated ciliopathies and which have mostly been linked to Hedgehog signalling defects. In addition, we have reviewed emerging evidence that PC dysfunctions could be directly or indirectly involved in the mechanisms underlying malformations of cerebral cortical development including primary microcephaly.

The application of chromosomal microarray analysis to the prenatal diagnosis of isolated mild ventriculomegaly.

OBJECTIVE: To investigate the clinical value of chromosomal microarray analysis (CMA) in the prenatal diagnosis of genetic abnormalities in fetal isolated mild ventriculomegaly. MATERIALS AND METHODS: This retrospective study reviewed 101 fetuses with isolated mild ventriculomegaly who had undergone invasive prenatal diagnosis at our hospital. CMA was performed in all cases to detect chromosomal aneuploidy as well as copy number variations (CNVs) that are too small to be detected by conventional karyotyping. Real time quantitative PCR (qPCR) or multiplex ligation dependent probe amplification (MLPA) was used to confirm all fetal CNVs <400 Kb. RESULTS: Except for three cases of chromosomal aneuploidy, CMA revealed pathogenic copy number variations (CNVs) in 3.0% (3/101) of the fetuses; these cases demonstrated involvement in the chromosomal regions 15q11.2, 1q21.1 and Xq27.3q28. Furthermore, we detected three likely pathogenic (3.0%) and two variants of uncertain significance (2.0%) among 101 fetuses diagnosed as isolated mild ventriculomegaly on ultrasound examination. CONCLUSION: Our study suggests that CNVs could aid in the risk assessment and genetic counseling in fetuses with isolated ventriculomegaly.

Derepression of sonic hedgehog signaling upon Gpr161 deletion unravels forebrain and ventricular abnormalities.

Inverse gradients of transcriptional repressors antagonize the transcriptional effector response to morphogens. However, the role of such inverse regulation might not manifest solely from lack of repressors. Sonic hedgehog (Shh) patterns the forebrain by being expressed ventrally; however, absence of antagonizing Gli3 repressor paradoxically cause insufficient pathway activation. Interestingly, lack of the primary cilia-localized G-protein-coupled receptor, Gpr161 increases Shh signaling in the mouse neural tube from coordinated lack of Gli3 repressor and Smoothened-independent activation. Here, by deleting Gpr161 in mouse neuroepithelial cells and radial glia at early mid-gestation we detected derepression of Shh signaling throughout forebrain, allowing determination of the pathophysiological consequences. Accumulation of cerebrospinal fluid (hydrocephalus) was apparent by birth, although usual causative defects in multiciliated ependymal cells or aqueduct were not seen. Rather, the ventricular surface was expanded (ventriculomegaly) during embryogenesis from radial glial overproliferation. Cortical phenotypes included polymicrogyria in the medial cingulate cortex, increased proliferation of intermediate progenitors and basal radial glia, and altered neocortical cytoarchitectonic structure with increased upper layer and decreased deep layer neurons. Finally, periventricular nodular heterotopia resulted from disrupted neuronal migration, while the radial glial scaffold was unaffected. Overall, suppression of Shh pathway during early mid-gestation prevents ventricular overgrowth, and regulates cortical gyration and neocortical/periventricular cytoarchitecture.

The third ventricle of the human fetal brain: Normative data and pathologic correlation. A 3D transvaginal neurosonography study.

OBJECTIVE: The objective of the study are to describe (a) the technical aspects and (b) the anatomical boundaries of the fetal third ventricle (3V) on the midsagittal sonographic view and to assess (c) different biometric parameters in normal and abnormal fetuses and (d) and their reproducibility. METHODS: This study included 67 normal and 50 CNS anomalies fetuses which include (1) obstructive severe ventriculomegaly (SVM; atrial width ≥ 15 mm), (2) moderate ventriculomegaly (10-14.9 mm), and (3) corpus callosum agenesis (ACC). All underwent transvaginal 3D neurosonography of the midsagittal view of the 3V. The following parameters were measured: area, perimeter, craniocaudal and anteroposterior (AP) diameters, interthalamic adhesion diameter (ITAD), wedge angle, and the ratio between the last 2 variables (ITAD/WA). Repeatability was also assessed. RESULTS: The ITAD and the ITAD/WA are significantly different between normal fetuses and the SVM (P ≤ .001). Interthalamic adhesion diameter of ≤7.1 mm is able to identify SVM with 98.6% accuracy (CI: 0.92-0.99). In ACC cases, the AP diameter is significantly shorter than both normal fetuses and ventriculomegaly. Intraobserver/interobserver reliability was good for most variables. CONCLUSIONS: Transvaginal neurosonography enables visualization of the normal and abnormal fetal third ventricle. An ITAD <7.1 identifies aqueductal stenosis as the likely etiology of severe ventriculomegaly with an accuracy of 98.6%.

A mutation in Ccdc39 causes neonatal hydrocephalus with abnormal motile cilia development in mice.

Pediatric hydrocephalus is characterized by an abnormal accumulation of cerebrospinal fluid (CSF) and is one of the most common congenital brain abnormalities. However, little is known about the molecular and cellular mechanisms regulating CSF flow in the developing brain. Through whole-genome sequencing analysis, we report that a homozygous splice site mutation in coiled-coil domain containing 39 (Ccdc39) is responsible for early postnatal hydrocephalus in the progressive hydrocephalus (prh) mouse mutant. Ccdc39 is selectively expressed in embryonic choroid plexus and ependymal cells on the medial wall of the forebrain ventricle, and the protein is localized to the axoneme of motile cilia. The Ccdc39prh/prh ependymal cells develop shorter cilia with disorganized microtubules lacking the axonemal inner arm dynein. Using high-speed video microscopy, we show that an orchestrated ependymal ciliary beating pattern controls unidirectional CSF flow on the ventricular surface, which generates bulk CSF flow in the developing brain. Collectively, our data provide the first evidence for involvement of Ccdc39 in hydrocephalus and suggest that the proper development of medial wall ependymal cilia is crucial for normal mouse brain development.

Hydrocephalus and arthrogryposis in an immunocompetent mouse model of ZIKA teratogeny: A developmental study.

The teratogenic mechanisms triggered by ZIKV are still obscure due to the lack of a suitable animal model. Here we present a mouse model of developmental disruption induced by ZIKV hematogenic infection. The model utilizes immunocompetent animals from wild-type FVB/NJ and C57BL/6J strains, providing a better analogy to the human condition than approaches involving immunodeficient, genetically modified animals, or direct ZIKV injection into the brain. When injected via the jugular vein into the blood of pregnant females harboring conceptuses from early gastrulation to organogenesis stages, akin to the human second and fifth week of pregnancy, ZIKV infects maternal tissues, placentas and embryos/fetuses. Early exposure to ZIKV at developmental day 5 (second week in humans) produced complex manifestations of anterior and posterior dysraphia and hydrocephalus, as well as severe malformations and delayed development in 10.5 days post-coitum (dpc) embryos. Exposure to the virus at 7.5-9.5 dpc induces intra-amniotic hemorrhage, widespread edema, and vascular rarefaction, often prominent in the cephalic region. At these stages, most affected embryos/fetuses displayed gross malformations and/or intrauterine growth restriction (IUGR), rather than isolated microcephaly. Disrupted conceptuses failed to achieve normal developmental landmarks and died in utero. Importantly, this is the only model so far to display dysraphia and hydrocephalus, the harbinger of microcephaly in humans, as well as arthrogryposis, a set of abnormal joint postures observed in the human setting. Late exposure to ZIKV at 12.5 dpc failed to produce noticeable malformations. We have thus characterized a developmental window of opportunity for ZIKV-induced teratogenesis encompassing early gastrulation, neurulation and early organogenesis stages. This should not, however, be interpreted as evidence for any safe developmental windows for ZIKV exposure. Late developmental abnormalities correlated with damage to the placenta, particularly to the labyrinthine layer, suggesting that circulatory changes are integral to the altered phenotypes.

Use of high-frequency ultrasound to study the prenatal development of cranial neural tube defects and hydrocephalus in Gldc-deficient mice.

OBJECTIVE: We used non-invasive high-frequency ultrasound (HFUS) imaging to investigate embryonic brain development in a mouse model for neural tube defects (NTDs) and non-ketotic hyperglycinemia (NKH). METHOD: Using HFUS, we imaged embryos carrying loss of function alleles of Gldc encoding glycine decarboxylase, a component of the glycine cleavage system in mitochondrial folate metabolism, which is known to be associated with cranial NTDs and NKH in humans. We serially examined the same litter during the second half of embryonic development and quantified cerebral structures. Genotype was confirmed using PCR. Histology was used to confirm ultrasound findings. RESULTS: High-frequency ultrasound allowed in utero detection of two major brain abnormalities in Gldc-deficient mouse embryos, cranial NTDs (exencephaly) and ventriculomegaly (corresponding with the previous finding of post-natal hydrocephalus). Serial ultrasound allowed individual embryos to be analysed at successive gestational time points. From embryonic day 16.5 to 18.5, the lateral ventricle volume reduced in wild-type and heterozygous embryos but increased in homozygous Gldc-deficient embryos. CONCLUSION: Exencephaly and ventriculomegaly were detectable by HFUS in homozygous Gldc-deficient mouse embryos indicating this to be an effective tool to study CNS development. Longitudinal analysis of the same embryo allowed the prenatal onset and progression of ventricle enlargement in Gldc-deficient mice to be determined. © 2017 The Authors. Prenatal Diagnosis published by John Wiley & Sons, Ltd.