Brain development and the genetics of brain development

Application of Three-Dimensional Pseudocontinuous Arterial Spin Labeling Perfusion Imaging in the Brains of Children With Autism

Objective

To explore the application of three-dimensional pseudocontinuous arterial spin labeling (3D-PCASL) perfusion imaging in the brains of children with autism and to understand the characteristics of cerebral blood perfusion in children with autism.

Methods

A total of 320 children with autism (160 men and 160 women) aged between 2 and 18 years and 320 age- and sex-matched healthy children participated in the study. All children were scanned by 3.0 T magnetic resonance axial T1 fluid-attenuated inversion recovery (FLAIR), T2 FLAIR, 3D-T1, and 3D-PCASL sequences. After postprocessing, cerebral blood flow (CBF) values in each brain region of children with autism and healthy children at the same age were compared and analyzed. Furthermore, CBF characteristics in each brain region of autistic children at various ages were determined.

Results

The CBF values of the frontal lobe, hippocampus, temporal lobe, and caudate nucleus of children with autism are lower than those of healthy children (P < 0.05). Additionally, as the ages of children with autism increase, the number of brain regions with decreased CBF values gradually increases. A receiver operating characteristic (ROC) analysis results show that the CBF values of the frontal lobe, hippocampus, temporal lobe, and caudate nucleus can distinguish children with autism [area under the ROC curve (AUC) > 0.05, P < 0.05].

Conclusion

The 3D-PCASL shows lower brain CBF values in children with autism.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier: ChiCTR2000034356.

Diagnostic assessment of foetal brain malformations with intra-uterine MRI versus perinatal post-mortem MRI

PURPOSE

To evaluate differences in diagnostic yield of intra-uterine foetal (iuMR) and post-mortem MRI (PMMR) for complex brain malformations, using autopsy as the reference standard.

METHODS

In this retrospective, multicentre study spanning 2 years, we reviewed 13 terminated singleton pregnancies with a prenatal ultrasound finding of complex foetal cerebral abnormalities, referred for both iuMR and PMMR. The iuMR and PMMR studies of the brain were reported independently by two groups of radiologists, blinded to each other's reports. Descriptive statistics were used to compare differences in intracranial abnormalities with autopsy (and genetic testing, where present) as reference standard.

RESULTS

The median gestational age at termination was 24.6 weeks (IQR 22-29) with median time between delivery and PMMR of 133 h (IQR 101-165). There was full concordance between iuMR and PMMR findings and autopsy in 2/13 (15.3%) cases. Partial concordance between both imaging modalities was present in 6/13 (46.2%) and total discordance in the remainder (5/13, 38.5%). When compared to autopsy, PMMR missed important key findings specifically for neuronal migration and cerebellar anomalies, whereas iuMR appeared to overcall CSF space abnormalities which were less crucial to reaching the final overall diagnosis.

CONCLUSIONS

iuMR should be performed to improve foetal phenotyping where there is a prenatal ultrasound for complex foetal brain abnormalities. Reliance on PMMR alone is likely to result in misdiagnosis in a majority of cases.

Excess social media use in normal populations is associated with amygdala-striatal but not with prefrontal morphology

This study aims to investigate the gray matter volume (GMV) of key neural systems possibly associated with Excess Social Media Use (ESMU) in the general user population. It employs a sex-balanced case (relatively high ESMU scores) - control (relatively low ESMU scores) design with 50 random university students who have reported varying levels of ESMU. The case and control groups included 25 subjects each. Brain volumes were calculated with Voxel-Based Morphometry techniques applied to structural MRI scans. Results based on voxel-wise and region-of-interest (ROI) analyses showed that the case group had reduced GMV in the bilateral amygdala and right ventral striatum. The GMV of the bilateral amygdala and right ventral striatum negatively correlated with ESMU scores in the voxel-wise analysis. No differences or correlations in relation to prefrontal regions were observed. Using the ROI analysis, the bilateral amygdala volumes correlated with ESMU scores, and insufficient evidence regarding the ventral striatum and ESMU was obtained. It is concluded that excess social media use in the general population is associated in part with GMV reduction in the bilateral amygdala, and possibly the striatum, but not in volumetric differences in prefrontal regions.

A refined approach to evaluating global developmental delay for the international medical community

BACKGROUND

Global developmental delay is usually defined as significant delay in two or more domains of development. Etiologic diagnosis generally proves difficult and the etiology remains undetermined in up to 62% of these children. Those in whom an etiology is established generally undergo an exhaustive and costly diagnostic evaluation, even though this may not change the medical or therapeutic management of the delay. The history and physical examination may provide up to 40% of etiologic diagnoses if adequately conducted.

METHODS

We performed a critical review of the literature on global developmental delay via PubMed.

RESULTS

Five major etiologic categories for global developmental delay were identified and traits of the history and physical examination suggestive for their diagnosis were described. Additionally, current diagnostic tools and their benefits and limitations were appraised.

CONCLUSIONS

We propose an improved approach to enhance clinical diagnosis in both resource-rich and resource-limited settings favoring early intervention and management.

De novo 393 kb microdeletion of 7p11.2 characterized by aCGH in a boy with psychomotor retardation and dysmorphic features

We report on a 27 month old boy presenting with psychomotor delay and dysmorphic features, mainly mild facial asymmetry, prominent cup-shaped ears, long eyelashes, open mouth appearance and slight abnormalities of the hands and feet. Array comparative genomic hybridization revealed a 393 kb microdeletion in 7p11.2. We discuss the possible involvement of CHCHD2, GBAS, MRPS17, SEPT14 and PSPH on our patient's phenotype. Additionally, we studied the expression of two other genes deleted in the patient, CCT6A and SUMF2, for which there is scarce data in the literature. Based on current knowledge and the de novo occurrence of this finding in our proband we presume that the aberration is likely to be pathogenic in our case. However, a single gene disorder, elsewhere in the genome or in this very region cannot be ruled out. Further elucidation of the properties of this chromosomal region, as well as of the role of the genes involved will be needed in order to draw safe conclusions regarding the association of the chromosomal deletion with the patient's features.

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We report in detail the clinical and cytogenetic findings of a 27-month old male.

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We compare our findings with current literature and online databases.

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We discuss the possible involvement of certain genes in our patient’s phenotype.

Congenital cytomegalovirus infection and brain clefting

BACKGROUND

Human cytomegalovirus, a major cause of permanent neurodevelopmental disability in children, frequently produces intracranial abnormalities, including calcifications and polymicrogyria, in infants with congenital cytomegalovirus infections. This report describes the features of cerebral cortical clefting, including schizencephaly, in children with congenital cytomegalovirus infection.

METHODS

This is a retrospective review of the medical records of infants and children with congenital cytomegalovirus infection evaluated at Primary Children's Medical Center, Salt Lake City, Utah, between 1999 and 2008.

FINDINGS

Twenty-five children with congenital cytomegalovirus infection were identified during this 10-year period; 23 (92%) had computed tomography and 17 (68%) had magnetic resonance imaging. Imaging was obtained at a median age of 6 months (mode 1 month or less). Of 15 children with confirmed congenital infections, 10 (66%) had polymicrogyria or abnormal gyral patterns, five (33%) had cleft cortical dysplasia, and two (13%) had schizencephaly. Of 10 children with suspected congenital cytomegalovirus infection, eight (80%) had polymicrogyria, two (20%) had cleft cortical dysplasia, and one (10%) had bilateral schizencephaly with calcifications. Seventeen of the 25 infants (68%) had intracranial calcifications.

INTERPRETATION

These results indicate that clefting, either as cleft cortical dysplasia or schizencephaly, is an important feature of congenital cytomegalovirus infection.

Application of in utero electroporation and live imaging in the analyses of neuronal migration during mouse brain development

Correct neuronal migration is crucial for brain architecture and function. During cerebral cortex development (corticogenesis), excitatory neurons generated in the proliferative zone of the dorsal telencephalon (mainly ventricular zone) move through the intermediate zone and migrate past the neurons previously located in the cortical plate and come to rest just beneath the marginal zone. The in utero electroporation technique is a powerful method for rapid gain- and loss-of-function studies of neuronal development, especially neuronal migration. This method enabled us to introduce genes of interest into ventricular zone progenitor cells of mouse embryos and to observe resulting phenotypes such as proliferation, migration, and cell morphology at later stages. In this Award Lecture Review, we focus on the application of the in utero electroporation method to functional analyses of cytoskeleton-related protein septin. We then refer to, as an advanced technique, the in utero electroporation-based real-time imaging method for analyses of cell signaling regulating neuronal migration. The in utero electroporation method and its application would contribute to medical molecular morphology through identification and characterization of the signaling pathways disorganized in various neurological and psychiatric disorders.

Neuropsychological functioning in a young adult case of schizencephaly

Schizencephaly is a rare neuromigrational/organizational disorder characterized by the development of cerebral clefts, which are typically associated with neurological sequelae including seizures, motor disturbances, and cognitive dysfunction. Although there are multiple case reports of schizencephaly and associated neurological sequelae, primarily in children, the literature regarding neuropsychological manifestations of schizencephaly is limited. This article reviews the case of a woman diagnosed with bilateral schizencephaly at age 29. Neuropsychological testing revealed intact intelligence and memory functioning. However, impairments were noted in attention, executive functioning, expressive language skills, visual-spatial abilities, and bilateral manual motor skills, all of which were adversely impacting her functional abilities (e.g., ability to be gainfully employed). Given the potential variability in deficits associated with schizencephaly, this case demonstrates the utility of neuropsychological evaluation for understanding cognitive and functional consequences of bilateral schizencephaly.

Septin 14 is involved in cortical neuronal migration via interaction with Septin 4

Septins are a family of conserved GTP/GDP-binding proteins implicated in a variety of cellular functions. We found that knockdown of Septin 14 or Septin 4 resulted in inhibition of cortical neuronal migration and defective leading process formation. These results suggest a novel function of septin in cortical development.

Septins are a family of conserved guanosine triphosphate/guanosine diphosphate-binding proteins implicated in a variety of cellular functions such as cell cycle control and cytokinesis. Although several members of septin family, including Septin 14 (Sept14), are abundantly expressed in nervous tissues, little is known about their physiological functions, especially in neuronal development. Here, we report that Sept14 is strongly expressed in the cortical plate of developing cerebral cortex. Knockdown experiments by using the method of in utero electroporation showed that reduction of Sept14 caused inhibition of cortical neuronal migration. Whereas cDNA encoding RNA interference-resistant Sept14 rescued the migration defect, the C-terminal deletion mutant of Sept14 did not. Biochemical analyses revealed that C-terminal coiled-coil region of Sept14 interacts with Septin 4 (Sept4). Knockdown experiments showed that Sept4 is also involved in cortical neuronal migration in vivo. In addition, knockdown of Sept14 or Sept4 inhibited leading process formation in migrating cortical neurons. These results suggest that Sept14 is involved in neuronal migration in cerebral cortex via interaction with Sept4.

Electroencephalogram in unilateral multilobar polymicrogyria with nonconvulsive status epilepticus

This case report presents the epileptic encephalopathy in an 11-year-old girl with multilobar unilateral polymicrogyria and focal nonconvulsive status epilepticus where high epileptogenicity was responsible for progressive and severe cognitive dysfunction. Nonconvulsive status epilepticus in epileptic encephalopathy with unilateral multilobar polymicrogyria has not been reported previously.

Notch signaling, brain development, and human disease

The Notch signaling pathway is central to a wide array of developmental processes in a number of organ systems, including hematopoiesis, somitogenesis, vasculogenesis, and neurogenesis. These processes involve maintenance of stem cell self-renewal, proliferation, specification of cell fate or differentiation, and apoptosis. Recent studies have led to the recognition of the role of the Notch pathway in early neurodevelopment, learning, and memory, as well as late-life neurodegeneration. This review summarizes what is currently known about the role of the Notch pathway in neural stem cells, gliogenesis, learning and memory, and neurologic disease.

Recognition of Zellweger syndrome in infancy

At least 29 proteins are required for assembly of the peroxisome, a single-membrane organelle responsible for many metabolic processes. A defect in any of these proteins affects the numerous biochemical functions of the cell. Many genetic disorders are associated with peroxisome defects. Zellweger syndrome, a rare autosomal recessive disorder, is one of the disorders that result from a deficiency in the assembly of the peroxisome. Impaired metabolism results in the accumulation of toxic metabolites and damages developing neural cells. This article provides an overview of peroxisome function and its effect on central nervous system development. It highlights the presentation, clinical features, and nursing care of infants with Zellweger syndrome. A meticulous systematic physical assessment enhances early recognition of the physical features of this disorder. Although magnetic resonance imaging detects polymicrogyria, a manifestation of abnormal neuronal migration that is often associated with Zellweger syndrome, the diagnosis is confirmed biochemically. An emphasis on family support through genetic counseling and the integration of palliative resources to enhance quality of life for infants and families with this lethal condition is provided.

Ndel1 operates in a common pathway with LIS1 and cytoplasmic dynein to regulate cortical neuronal positioning

Correct neuronal migration and positioning during cortical development are essential for proper brain function. Mutations of the LIS1 gene result in human lissencephaly (smooth brain), which features misplaced cortical neurons and disarrayed cerebral lamination. However, the mechanism by which LIS1 regulates neuronal migration remains unknown. Using RNA interference (RNAi), we found that the binding partner of LIS1, NudE-like protein (Ndel1, formerly known as NUDEL), positively regulates dynein activity by facilitating the interaction between LIS1 and dynein. Loss of function of Ndel1, LIS1, or dynein in developing neocortex impairs neuronal positioning and causes the uncoupling of the centrosome and nucleus. Overexpression of LIS1 partially rescues the positioning defect caused by Ndel1 RNAi but not dynein RNAi, whereas overexpression of Ndel1 does not rescue the phenotype induced by LIS1 RNAi. These results provide strong evidence that Ndel1 interacts with LIS1 to sustain the function of dynein, which in turn impacts microtubule organization, nuclear translocation, and neuronal positioning.

Sonography of the fetal central nervous system

This article presents a general overview of fetal sonography and an approach to the sonographic evaluation of the fetal central nervous system. Annotated images of anomalies of the fetal head, brain, spine, face, and neck are shown. Sonographic technique,including the choice of transducers and imaging windows is presented. The complementary relationship of fetal neurosonography and fetal MR imaging is covered, and the strengths and weaknesses of each modality are discussed.