Germline mutations in the homeobox gene EMX2 in patients with severe schizencephaly

Schizencephaly Associated With Bipolar Affective Disorder

Schizencephaly is a rare congenital anomaly characterized by the formation of abnormal clefts in the brain. Despite the association of psychotic symptoms with various brain abnormalities or insults, their occurrence in individuals with schizencephaly is relatively infrequent. The association of bipolar disorder, with or without psychosis, with schizencephaly is rarer. A systematic search on PubMed using "Schizencephaly AND Bipolar Disorder" yielded only four case studies specifically addressing the connection between these two conditions. Here, we present a case of a 22-year-old male patient with a history of childhood seizures who developed first episode psychosis along with manic symptoms and was found to have closed-lip schizencephaly.

[Clinical and functional disturbances in epilepsy patients with schizencephaly]

OBJECTIVE

To study the features of diagnosing and predicting structural epilepsy in children with schizencephaly (SE) based on the analysis of clinical, electrophysiological and neuroimaging results.

MATERIAL AND METHODS

Fifteen patients with epilepsy and SE (seven boys and eight girls), aged from 3 months to 14 years, were examined.

RESULTS

Unilateral SE was detected in ten patients (closed - in four, open - in six), bilateral open SE was detected in five patients. The predominant localization of the anomaly is in the frontal region. In 100% of cases, cognitive and motor impairments of varying severity were detected. In the study group, 11 patients (73.3%) were diagnosed with epilepsy before the age of 6 years. The clinical presentations of epilepsy in children with SE included focal seizures in ten patients (73.3%), epileptic spasms in three patients (20.0%), focal seizures with secondary generalization in five (33.3%), atonic - in one child (6.7%). Refractory epilepsy was noted in 26.7% children with SE, and the absence of positive electroencephalographic changes in 40% of children.

CONCLUSIONS

The extent of structural brain damage in SE in patients with epilepsy correlates with the degree of cognitive and motor deficits. The form of epilepsy, the semiotics of epileptic seizures, and the effectiveness of antiepileptic therapy do not depend on the type of SE, but correlate with the extent of cortical disorders.

From mesenchymal niches to engineered in vitro model systems: Exploring and exploiting biomechanical regulation of vertebrate hedgehog signalling

Tissue patterning is the result of complex interactions between transcriptional programs and various mechanical cues that modulate cell behaviour and drive morphogenesis. Vertebrate Hedgehog signalling plays key roles in embryogenesis and adult tissue homeostasis, and is central to skeletal development and the osteogenic differentiation of mesenchymal stem cells. The expression of several components of the Hedgehog signalling pathway have been reported to be mechanically regulated in mesodermal tissue patterning and osteogenic differentiation in response to external stimulation. Since a number of bone developmental defects and skeletal diseases, such as osteoporosis, are directly linked to aberrant Hedgehog signalling, a better knowledge of the regulation of Hedgehog signalling in the mechanosensitive bone marrow-residing mesenchymal stromal cells will present novel avenues for modelling these diseases and uncover novel opportunities for extracellular matrix-targeted therapies. In this review, we present a brief overview of the key molecular players involved in Hedgehog signalling and the basic concepts of mechanobiology, with a focus on bone development and regeneration. We also highlight the correlation between the activation of the Hedgehog signalling pathway in response to mechanical cues and osteogenesis in bone marrow-derived mesenchymal stromal cells. Finally, we propose different tissue engineering strategies to apply the expanding knowledge of 3D material-cell interactions in the modulation of Hedgehog signalling in vitro for fundamental and translational research applications.

Identifying enhancer properties associated with genetic risk for complex traits using regulome-wide association studies

Genetic risk for complex traits is strongly enriched in non-coding genomic regions involved in gene regulation, especially enhancers. However, we lack adequate tools to connect the characteristics of these disruptions to genetic risk. Here, we propose RWAS (Regulome Wide Association Study), a new application of the MAGMA software package to identify the characteristics of enhancers that contribute to genetic risk for disease. RWAS involves three steps: (i) assign genotyped SNPs to cell type- or tissue-specific regulatory features (e.g., enhancers); (ii) test associations of each regulatory feature with a trait of interest for which genome-wide association study (GWAS) summary statistics are available; (iii) perform enhancer-set enrichment analyses to identify quantitative or categorical features of regulatory elements that are associated with the trait. These steps are implemented as a novel application of MAGMA, a tool originally developed for gene-based GWAS analyses. Applying RWAS to interrogate genetic risk for schizophrenia, we discovered a class of risk-associated AT-rich enhancers that are active in the developing brain and harbor binding sites for multiple transcription factors with neurodevelopmental functions. RWAS utilizes open-source software, and we provide a comprehensive collection of annotations for tissue-specific enhancer locations and features, including their evolutionary conservation, AT content, and co-localization with binding sites for hundreds of TFs. RWAS will enable researchers to characterize properties of regulatory elements associated with any trait of interest for which GWAS summary statistics are available.

Enhancers are regulatory regions that influence gene expression via the binding of transcription factors. Risk for many heritable diseases is enriched in regulatory regions, including enhancers. In this study, we introduce a novel application of the MAGMA software tool that enables testing for associations between enhancer attributes and risk, and we use this method to determine the enhancer characteristics that are associated with risk for schizophrenia. We found that enhancers associated with schizophrenia risk are both evolutionarily conserved and in physical contact with mutation-intolerant genes, many of which have neurodevelopmental functions. Risk-associated enhancers are also AT-rich and contain binding sites for neurodevelopmental transcription factors.

Of numbers and movement - understanding transcription factor pathogenesis by advanced microscopy

Transcription factors (TFs) are life-sustaining and, therefore, the subject of intensive research. By regulating gene expression, TFs control a plethora of developmental and physiological processes, and their abnormal function commonly leads to various developmental defects and diseases in humans. Normal TF function often depends on gene dosage, which can be altered by copy-number variation or loss-of-function mutations. This explains why TF haploinsufficiency (HI) can lead to disease. Since aberrant TF numbers frequently result in pathogenic abnormalities of gene expression, quantitative analyses of TFs are a priority in the field. In vitro single-molecule methodologies have significantly aided the identification of links between TF gene dosage and transcriptional outcomes. Additionally, advances in quantitative microscopy have contributed mechanistic insights into normal and aberrant TF function. However, to understand TF biology, TF-chromatin interactions must be characterised in vivo, in a tissue-specific manner and in the context of both normal and altered TF numbers. Here, we summarise the advanced microscopy methodologies most frequently used to link TF abundance to function and dissect the molecular mechanisms underlying TF HIs. Increased application of advanced single-molecule and super-resolution microscopy modalities will improve our understanding of how TF HIs drive disease.

Unilateral right closed-lip schizencephaly

Schizencephaly is a rare central nervous system (CNS) malformation secondary to neuronal migration defects. The pathogenesis is complex and is secondary to environmental and genetic factors. Clinically, the majority of patients present with varying degrees of motor and psychological disturbances. Imaging plays a cornerstone in the diagnosis by identifying the characteristic lesional features and recognising other associated abnormalities such as an absent septum pellucidum and corpus callosum dysgenesis. Here, we present a male paediatric case who presented with an interestingly asymptomatic unilateral right closed-lip schizencephaly and review the aetiology, clinical presentation and imaging characteristics of the disease and associated literature.

A missense mutation in SNRPE linked to non-syndromal microcephaly interferes with U snRNP assembly and pre-mRNA splicing

Malfunction of pre-mRNA processing factors are linked to several human diseases including cancer and neurodegeneration. Here we report the identification of a de novo heterozygous missense mutation in the SNRPE gene (c.65T>C (p.Phe22Ser)) in a patient with non-syndromal primary (congenital) microcephaly and intellectual disability. SNRPE encodes SmE, a basal component of pre-mRNA processing U snRNPs. We show that the microcephaly-linked SmE variant is unable to interact with the SMN complex and as a consequence fails to assemble into U snRNPs. This results in widespread mRNA splicing alterations in fibroblast cells derived from this patient. Similar alterations were observed in HEK293 cells upon SmE depletion that could be rescued by the expression of wild type but not mutant SmE. Importantly, the depletion of SmE in zebrafish causes aberrant mRNA splicing alterations and reduced brain size, reminiscent of the patient microcephaly phenotype. We identify the EMX2 mRNA, which encodes a protein required for proper brain development, as a major mis-spliced down stream target. Together, our study links defects in the SNRPE gene to microcephaly and suggests that alterations of cellular splicing of specific mRNAs such as EMX2 results in the neurological phenotype of the disease.

In higher eukaryotes, the protein coding genes are first transcribed as precursor mRNAs (pre-mRNAs) and further processed by the spliceosome to form the mature mRNA for translation. Malfunction of pre-mRNA processing factors are linked to several human diseases including cancer and neurodegeneration. Here we report the identification of a de novo heterozygous missense mutation in the SNRPE/SmE gene in a patient with non-syndromal primary (congenital) microcephaly and intellectual disability. The effect of identified de novo mutation on SNRPE/SmE was characterized in vitro. The zebrafish was used as in vivo model to further dissect the physiological consequence and pathomechanism. Finally, the EMX2 gene was identified as one of the major down stream target genes responsible for the phenotype. Our study links defects in the SNRPE/SmE gene to microcephaly and provides the new pathogenic mechanism for microcephaly.

Schizencephaly: A Review of 734 Patients

BACKGROUND

Schizencephaly is a rare congenital cerebral malformation associated with serious neurological manifestations. The number of studies regarding schizencephaly is limited.

METHODS

We conducted a literature review and extracted data from the case reports. Of 199 articles retrieved, 156 articles (734 patients) met our inclusion criteria.

RESULTS

Patient characteristics included microcephaly (41.5% of patients), seizures (74.1%), bilateral cleft (41.4%), open lip (61.3%), septo-optic dysplasia (69.1%), and ventricular dilation (60.5%). The majority of clefts were in the frontal and parietal lobes. When these potential association factors were assessed by univariate logistic regression microcephaly (OR = 21.75, P < 0.001), corpus callosum agenesis (OR = 9, P < 0.001), motor impairments (OR = 6.21, P < 0.001), and bilateral clefts (OR = 6.31, P < 0.001) seems to have the strongest association, but also age at diagnosis <10 years (OR = 1.05, P < 0.001), right (OR = 1.85, P = 0.001) or left (OR = 2.71, P < 0.001) side clefts and septum pellucidum (OR = 3.7, P = 0.002) agenesis were associated with neurocognitive dysfunctions.

CONCLUSIONS

We describe novel findings with practical implications for predicting neurocognitive outcomes in patients with schizencephaly. Most patients had neurological impairments including motor (90.0%) or cognitive (77.5%) dysfunctions. Bilateral clefts, motor impairment, microcephaly, and corpus callosum agenesis were strongly associated with neurocognitive impairment. A lack of large cohorts of patients with schizencephaly prevented comparison of our results; most previous studies are case reports or small case series.

Pregnancy management and outcome in patients with four different tetrahydrobiopterin disorders

INTRODUCTION

Inborn errors of tetrahydrobiopterin (BH4) biosynthesis or recycling are a group of very rare neurometabolic diseases. Following growing awareness and improved availability of drug treatment the number of patients with BH4 disorders reaching adulthood is constantly increasing. Pregnancy care of patients with these disorders is therefore a new challenge for clinicians.

METHODS

This retrospective study summarises for the first time clinical and biochemical monitoring data of 16 pregnancies in seven women with different disorders of BH4 metabolism and evaluates treatment regimens before and during pregnancy in relation to the obstetrical outcome and paediatric follow-up.

RESULTS

Worsening of pre-existing neurological symptoms or occurrence of new symptoms during pregnancy was not observed in most of the cases. Treatment regimens remained mostly unchanged. Pregnancies were not complicated by disease-specific features. Organ abnormalities, miscarriage, prematurity, IUGR and chromosomal changes were occasionally reported, without showing any association with the standard drug treatment for BH4 deficiencies.

CONCLUSION

Although our data on 16 pregnancies in seven patients did not present any association of standard drug treatment with an increased rate of pregnancy complications, abnormal obstetrical or paediatric outcome, an intensive clinical and biochemical supervision by a multidisciplinary team before, during and after the pregnancy in any BH4 deficiency is essential since available data on pregnancies in patients with BH4 deficiencies is limited.

Schizencephaly revisited

Purpose

In this paper, I will report the range of appearances of schizencephaly in children and fetuses by reviewing a 10-year experience from a single centre and detail classification systems for the different forms of schizencephaly. This will lead to re-assessment of possible aetiological and mechanistic causes of schizencephaly.

Methods

All cases of pediatric and fetal schizencephaly were located on the local database between 2007 and 2016 inclusive. The studies were reviewed for the presence, location and type of schizencephaly, as well as the state of the (cavum) septum pellucidum, the location of the fornices and the presence of other brain abnormalities.

Results

The review included 21 children and 11 fetuses with schizencephaly. Schizencephaly (type 1) was found in 9% of children but no fetuses, schizencephaly (type 2) was present in 67% of the pediatric cases and in 45% of fetuses, whilst schizencephaly (type 3) was present in approximately 24% of children and 55% of fetuses. Other brain abnormalities were found in 67% of children and 55% of fetuses.

Conclusion

I have proposed a new system for classifying schizencephaly that takes into account all definitions of the abnormality in the literature. Using that approach, I have described the appearances and associations of pediatric and fetal cases of schizencephaly from a single centre. Review of the current literature appears to favour an acquired destructive aetiology for most cases of schizencephaly, and I have proposed a mechanism to explain the cortical formation abnormalities found consistently in and around areas of schizencephaly.

A universal mammalian vaccine cell line substrate

Using genome-wide small interfering RNA (siRNA) screens for poliovirus, influenza A virus and rotavirus, we validated the top 6 gene hits PV, RV or IAV to search for host genes that when knocked-down (KD) enhanced virus permissiveness and replication over wild type Vero cells or HEp-2 cells. The enhanced virus replication was tested for 12 viruses and ranged from 2-fold to >1000-fold. There were variations in virus-specific replication (strain differences) across the cell lines examined. Some host genes (CNTD2, COQ9, GCGR, NDUFA9, NEU2, PYCR1, SEC16G, SVOPL, ZFYVE9, and ZNF205) showed that KD resulted in enhanced virus replication. These findings advance platform-enabling vaccine technology, the creation of diagnostic cells substrates, and are informative about the host mechanisms that affect virus replication in mammalian cells.

EMX2 gene expression predicts liver metastasis and survival in colorectal cancer

BACKGROUND

The Empty Spiracles Homeobox (EMX-) 2 gene has been associated with regulation of growth and differentiation in neuronal development. While recent studies provide evidence that EMX2 regulates tumorigenesis of various solid tumors, its role in colorectal cancer remains unknown. We aimed to assess the prognostic significance of EMX2 expression in stage III colorectal adenocarcinoma.

METHODS

Expression levels of EMX2 in human colorectal cancer and adjacent mucosa were assessed by qRT-PCR technology, and results were correlated with clinical and survival data. siRNA-mediated knockdown and adenoviral delivery-mediated overexpression of EMX2 were performed in order to investigate its effects on the migration of colorectal cancer cells in vitro.

RESULTS

Compared to corresponding healthy mucosa, colorectal tumor samples had decreased EMX2 expression levels. Furthermore, EMX2 down-regulation in colorectal cancer tissue was associated with distant metastasis (M1) and impaired overall patient survival. In vitro knockdown of EMX2 resulted in increased tumor cell migration. Conversely, overexpression of EMX2 led to an inhibition of tumor cell migration.

CONCLUSIONS

EMX2 is frequently down-regulated in human colorectal cancer, and down-regulation of EMX2 is a prognostic marker for disease-free and overall survival. EMX2 might thus represent a promising therapeutic target in colorectal cancer.

Disruptions in asymmetric centrosome inheritance and WDR62-Aurora kinase B interactions in primary microcephaly

Recessive mutations in WD repeat domain 62 (WDR62) cause microcephaly and a wide spectrum of severe brain malformations. Disruption of the mouse ortholog results in microcephaly underlain by reduced proliferation of neocortical progenitors during late neurogenesis, abnormalities in asymmetric centrosome inheritance leading to neuronal migration delays, and altered neuronal differentiation. Spindle pole localization of WDR62 and mitotic progression are defective in patient-derived fibroblasts, which, similar to mouse neocortical progenitors, transiently arrest at prometaphase. Expression of WDR62 is closely correlated with components of the chromosome passenger complex (CPC), a key regulator of mitosis. Wild type WDR62, but not disease-associated mutant forms, interacts with the CPC core enzyme Aurora kinase B and staining of CPC components at centromeres is altered in patient-derived fibroblasts. Our findings demonstrate critical and diverse functions of WDR62 in neocortical development and provide insight into the mechanisms by which its disruption leads to a plethora of structural abnormalities.

Telencephalic Flexure and Malformations of the Lateral Cerebral (Sylvian) Fissure

After sagittal division of the prosencephalon at 4.5 weeks of gestation, the early fetal cerebral hemisphere bends or rotates posteroventrally from seven weeks of gestation. The posterior pole of the telencephalon thus becomes not the occipital but the temporal lobe as the telencephalic flexure forms the operculum and finally the lateral cerebral or Sylvian fissure. The ventral part is infolded to become the insula. The frontal and temporal lips of the Sylvian fissure, as well as the insula, all derive from the ventral margin of the primitive telencephalon, hence may be influenced by genetic mutations with a ventrodorsal gradient of expression. The telencephalic flexure also contributes to a shift of the hippocampus from a dorsal to a ventral position, the early rostral pole of the hippocampus becoming caudal and dorsal becoming ventral. The occipital horn is the most recent recess of the lateral ventricle, hence most vulnerable to anatomic variations that affect the calcarine fissure. Many major malformations include lack of telencephalic flexure (holoprosencephaly, extreme micrencephaly) or dysplastic Sylvian fissure (lissencephalies, hemimegalencephaly, schizencephaly). Although fissures and sulci are genetically programmed, mechanical forces of growth and volume expansion are proposed to be mainly extrinsic (including ventricles) for fissures and intrinsic for sulci. In fetal hydrocephalus, the telencephalic flexure is less affected because ventricular dilatation occurs later in gestation. Flexures can be detected prenatally by ultrasound and fetal magnetic resonance imaging and should be described neuropathologically in cerebral malformations.

Successful surgery for refractory seizures associated with bilateral schizencephaly: two case reports and literature review

Schizencephaly is a rare malformation of cortical development resulting from cell migration defects that occur unilaterally or bilaterally. The type of the schizencephalic cleft can be open lip or closed lip. Patients suffering from refractory seizures secondary to schizencephaly should be considered for surgical treatment. In this paper, we retrospectively analyzed two patients with confirmed schizencephaly and intractable seizures. The evaluation methods included a medical history assessment, a neurological examination and magnetic resonance imaging (MRI). Continuous intracranial video-electroencephalogram (vEEG) monitoring with surface electrodes and deep electrodes was evaluated to confirm the epileptogenic zones associated with the schizencephalic lesions. Cortical electrical stimulation was performed to evaluate the neurophysiology of the relevant brain regions. Epileptic focus resection was performed close to the schizencephalic cleft according to the results of intracranial EEG and stimulation while preserving neurological functions. MRI revealed bilateral open lip schizencephaly in one patient and closed lip schizencephaly in the other patient. The epileptogenic zones were localized close to the schizencephalic clefts. The seizure outcome was Engel's class Ia in both patients at 1-year follow-up. No significant neurological deficits were found, and their activities of daily life were significantly improved. We conclude that abnormal cortex near the schizencephalic clefts may display an extrinsic epileptogenicity. Accurate localization of the epileptogenic zones using intracranial EEG and electrical stimulation can lead to a seizure-free outcome in patients with refractory epilepsy associated with schizencephaly.

Prenatal Diagnosis and Postnatal Outcome of Schizencephaly

The aim of this study was to present our experience with 5 cases of fetal schizencephaly in terms of prenatal diagnostic features, and postnatal outcome. The database of prenatal diagnosis unit was searched for antenatally diagnosed cases with schizencephaly. Maternal characteristics, ultrasonography, prenatal-postnatal magnetic resonance imaging (MRI) findings, and postnatal outcome were noted. Of 5 cases, 2 had definitive prenatal diagnoses on ultrasound and 3 cases were diagnosed by fetal MRI. All cases had cerebral cortical migration anomalies including polymicrogyria, subependymal heterotopia, and lissencephaly, and 2 cases had additional extracranial malformations. Three cases showed regression of the cerebral clefts on follow-up postnatal MRIs. Three cases had moderate to severe psychomotor retardation, and 1 case needed repeated ventriculoperitoneal shunt operation due to hydrocephaly. Prenatal diagnosis of schizencephaly with ultrasonography is not straightforward and required further evaluation with fetal MRI. Additional cerebral anomalies worsen the prognosis of schizencephaly.

The homeobox gene EMX2 is a prognostic and predictive marker in malignant pleural mesothelioma

OBJECTIVES

Malignant pleural mesothelioma (MPM) is a highly aggressive neoplasm with a poor prognosis and limited treatment options. EMX2 is a homeobox transcription factor that may regulate key developmental pathways known to promote tumorigenesis. In this study, we evaluated the prognostic and predictive significance of EMX2 expression in MPM.

MATERIALS AND METHODS

Fifty surgically resected MPM specimens were studied. Quantitative real-time RT-PCR was used to analyze EMX2 mRNA expression. Association of EMX2 levels with clinical outcomes was evaluated with using the Kaplan-Meier method and a multivariate Cox proportional hazards regression model.

RESULTS

EMX2 expression was significantly associated with IMIG stage (p<0.001) and smoking history (p=0.006). Cox hazard regression modeling identified low-EMX2 expression as a negative prognostic factor in progression-free survival by both univariate (p=0.002) and multivariate analysis (p=0.002). Kaplan-Meier analysis revealed significant differences in progression-free survival between low- and high-EMX expressing groups in all patients (p=0.001), and also when grouped by early (I/II) stage disease (p<0.001), patients undergoing pleurectomy (p<0.001) and patients with an epitheliod subtype (p<0.004). Furthermore, EMX2 expression predicted response to neoadjuvant chemotherapy. High-EMX2 expression was associated with decreased progression-free survival after neoadjuvant therapy, suggesting that induction therapy should be avoided in these patients.

CONCLUSIONS

EMX2 expression is downregulated in advanced cases of malignant pleural mesothelioma and may serve as an important prognostic and predictive molecular biomarker of progression-free survival.

Polymicrogyria: a common and heterogeneous malformation of cortical development

Polymicrogyria (PMG) is one of the most common malformations of cortical development. It is characterized by overfolding of the cerebral cortex and abnormal cortical layering. It is a highly heterogeneous malformation with variable clinical and imaging features, pathological findings, and etiologies. It may occur as an isolated cortical malformation, or in association with other malformations within the brain or body as part of a multiple congenital anomaly syndrome. Polymicrogyria shows variable topographic patterns with the bilateral perisylvian pattern being most common. Schizencephaly is a subtype of PMG in which the overfolded cortex lines full-thickness clefts connecting the subarachnoid space with the cerebral ventricles. Both genetic and non-genetic causes of PMG have been identified. Non-genetic causes include congenital cytomegalovirus infection and in utero ischemia. Genetic causes include metabolic conditions such as peroxisomal disorders and the 22q11.2 and 1p36 continguous gene deletion syndromes. Mutations in over 30 genes have been found in association with PMG, especially mutations in the tubulin family of genes. Mutations in the (PI3K)-AKT pathway have been found in association PMG and megalencephaly. Despite recent genetic advances, the mechanisms by which polymicrogyric cortex forms and causes of the majority of cases remain unknown, making diagnostic and prenatal testing and genetic counseling challenging. This review summarizes the clinical, imaging, pathologic, and etiologic features of PMG, highlighting recent genetic advances.

Bilateral schizencephaly Type II

BACKGROUND

Schizencephaly is one of the most severe forms of neuronal migration defects and is an extremely rare cause of seizure disorder.

CASE DETAILS

We report a case of bilateral schizencephaly (Type II) presenting as seizure disorder since birth.

DISCUSSION

This case is rare because of the relatively benign features compared to other reported cases.

CONCLUSION

Compared to other cases, this patient has normal cognitive and motor functioning. Given the scant literature on schizencephaly in India's paediatric population, this case highlights the possibility of a very rare entity associated with seizures. MRI can detect this condition.

Clinical and radiologic features of unilateral and bilateral schizencephaly in polish pediatric patients

Schizencephaly is a rare and severe congenital brain defect. Its etiology is not unequivocal and its clinical course differs with every case. The aim of the study was to analyze correlations between clinical and radiologic features of schizencephaly in Polish patients. The study group consisted of 25 children. Epileptic seizures were observed in 60% of cases and in 32% epilepsy was drug resistant. Generalized hypotonia was found in 24%, spastic diparesis in 48%, and spastic hemiparesis in 28% of cases. Seizures were more frequent in the bilateral than unilateral schizencephaly subgroup (72% vs 29%, P = .045). There was a correlation between the presence of the bilateral type II schizencephaly and the occurrence of seizures (P = .002, r = 0.578). There is a correlation between the type of schizencephaly and the presence of seizures in Polish pediatric patients. In most of the patients, schizencephaly leads to developmental retardation and epileptic seizures.

Correlation of prenatal and postnatal MRI findings in schizencephaly

BACKGROUND AND PURPOSE

Schizencephaly is a rare malformation of the brain characterized by a gray matter-lined defect extending from the pial surface to the lateral ventricles. The purpose of this study was to correlate imaging findings of schizencephaly and associated anomalies on fetal and postnatal MR imaging and assess possible changes that may occur from the prenatal-to-postnatal state.

MATERIALS AND METHODS

A retrospective review of subjects with schizencephaly who had both pre- and postnatal MR imaging was performed. Subject age, cleft type, number, location, and features of the defects and associated anomalies were recorded. Normalized dimensions of the defect and ipsilateral ventricle were measured and correlated to changes in the clefts between pre- and postnatal imaging.

RESULTS

Ten subjects with 18 clefts (8 bilateral) were included. Most defects (83%) were open on prenatal MR imaging, but 47% of those were found to have subsequently closed on postnatal imaging. Evidence of prior hemorrhage was seen in 83%. Prenatal MR imaging detected all cases of an absent septum pellucidum but detected a fraction of gross polymicrogyria and missed all cases of optic nerve hypoplasia. The normalized ipsilateral ventricular and inner and middle width dimensions of the defects were significantly decreased at postnatal imaging (P < .05). The widths of the defects, ventricular width, and presence of hemorrhage were not predictors of closure of prenatally diagnosed open defects (P > .05).

CONCLUSIONS

In our series, nearly half of prenatally open schizencephaly defects had closed on postnatal imaging. Prenatal MR imaging was only able to demonstrate some of the associated anomalies.

Schizencephaly: association with young maternal age, alcohol use, and lack of prenatal care

Schizencephaly is a rare malformation of cortical development characterized by congenital clefts extending from the pial surface to the lateral ventricle that are lined by heterotopic gray matter. The clinical presentation is variable and can include motor or cognitive impairment and epilepsy. The causes of schizencephaly are heterogeneous and can include teratogens, prenatal infection, or maternal trauma. Reported genetic causes include chromosomal aneuploidy, EMX2 mutations, and possible autosomal recessive familial cases based on recurrence in siblings. In an effort to identify risk factors for schizencephaly, we conducted a survey of 48 parents or primary caretakers of patients with schizencephaly born between 1983 and 2004. We discovered that young maternal age, lack of prenatal care, and alcohol use were all significantly associated with risk of schizencephaly. Our results suggest that there are important nongenetic, intrauterine events that predispose to schizencephaly.

Diffuse malformations of cortical development

Malformations of cortical development (MCD) represent a major cause of developmental disabilities and severe epilepsy. Advances in imaging and genetics have improved the diagnosis and classification of these conditions. Up to now, eight genes have been involved in different types of MCD. Lissencephaly-pachygyria and subcortical band heterotopia (SBH) represent a malformative spectrum resulting from mutations of either LIS1 or DCX genes. LIS1 mutations cause a more severe malformation in the posterior brain regions. DCX mutations usually cause anteriorly predominant lissencephaly in males and SBH in female patients. Additional forms are X-linked lissencephaly with corpus callosum agenesis and ambiguous genitalia associated with mutations of the ARX gene. Lissencephaly with cerebellar hypoplasia (LCH) encompass heterogeneous disorders named LCH types a to d. LCHa is related to mutation in LIS1 or DCX, LCHb with mutation of the RELN gene, and LCHd could be related to the TUBA1A gene. Polymicrogyria encompasses a wide range of clinical, etiological, and histological findings. Among several syndromes, recessive bilateral fronto-parietal polymicrogyria has been associated with mutations of the GPR56 gene. Bilateral perisylvian polymicrogyria has been associated with mutations in the SRPX2 gene in a few individuals and with linkage to chromosome Xq28 in a some other families. X-linked bilateral periventricular nodular heterotopia (PNH) consists of PNH with focal epilepsy in females and prenatal lethality in males. Filamin A (FLNA) mutations have been reported in some families and in sporadic patients. It is possible to infer the most likely causative gene by brain imaging studies and other clinical findings.

Malformations of cortical development

Structural abnormalities of the brain are increasingly recognized in patients that suffer from pharmacoresistant focal epilepsies by applying high-resolution imaging techniques. In many of these patients, epilepsy surgery results in control of seizures. Neuropathologically, a broad spectrum of malformations of cortical development (MCD) is observed in respective surgical brain samples. These samples provide a unique basis to further understand underlying pathomechanisms by molecular approaches and develop improved diagnostics and entirely new therapeutic perspectives. Here we provide a comprehensive description of neuropathological findings, available classification systems as well as molecular mechanisms of MCDs. We emphasize the recently published ILEA classification system for focal cortical dysplasias (FCDs), which are now histopathologically distinguished as types I to III. However, this revised classification system represents a major challenge for molecular neuropathologists, as the underlying pathomechanisms in virtually all FCD entities will need to be specified in detail. The fact that only recently, the mammalian target of rapamycin (mTOR)-antagonist Everolimus has been introduced as a treatment of epilepsies in the context of tuberous sclerosis-associated brain lesions is a striking example of a successful translational "bedside to bench and back" approach. Hopefully, the exciting clinico-pathological developments in the field of MCDs will in short term foster further therapeutic breakthroughs for the frequently associated medically refractory epilepsies.

Cortical dysplasia: a possible substrate for brain tumors

The similarities between brain tumor stem cells and neural stem cells suggest a possible stem cell origin of tumorigenesis. Recently, cells with features of stem cells have been observed in lesions of adult and pediatric cortical dysplasia (CD). Given the evidence for a close relationship between CD and certain brain tumors, together with the finding that CD neural stem cells/progenitors are abnormally developed, we propose that CD is a possible substrate for brain tumors. The neural stem cells/progenitors in CD have accumulating abnormalities, and these abnormal stem/progenitor cells may be the initiating, transformed cells of brain tumors, when subsequently exposed to a carcinogen.

Malformations of cortical development with good clinical outcome: a case report and review of literature

Malformations of cortical development (MCD) are important causes of chronic epilepsy. MCD encompass many varied disorders with diverse clinical manifestations. Schizencephaly, one of the MCD, is known to be complicated by various types of epilepsy, most of which are intractable. We treated a 28-year-old man with epilepsy, characterised by unprovoked generalised tonic-clonic seizures accompanied by MCD. Brain MRI detected multiple malformations including septum pellucidum defect, partial corpus callosum defect, schizencephaly, right hippocampal atrophy, cerebellar atrophy and cerebellum atrophy. 99m Tc-ethylcysteinate dimer single photon emission CT showed decreased cerebral blood flow (CBF), and the morphology of CBF defects overlapped with the anomalous findings on MRI. The clinical outcome of the patient was good despite his severe brain malformations. Although the reason of this discrepancy is unclear, the outcomes of social function and epileptic seizures may be relatively good despite severe MCD in some patients.

Development and dysgenesis of the cerebral cortex: malformations of cortical development

The cerebral cortex develops in several stages from a pseudostratified epithelium at 5 weeks to an essentially complete cortex at 47 weeks. Cortical connectivity starts with thalamocortical connections in the 3rd trimester only and continues until well after birth. Vascularity adapts to proliferation and connectivity. Malformations of cortical development are classified into disorders of specification, proliferation/apoptosis, migration, and organization. However, all processes are intermingled, as for example a dysplastic cell may migrate incompletely and not connect appropriately. However, this classification is convenient for didactic purposes as long as the complex interactions between the different processes are kept in mind.

Association of common genetic variants in GPCPD1 with scaling of visual cortical surface area in humans

Visual cortical surface area varies two- to threefold between human individuals, is highly heritable, and has been correlated with visual acuity and visual perception. However, it is still largely unknown what specific genetic and environmental factors contribute to normal variation in the area of visual cortex. To identify SNPs associated with the proportional surface area of visual cortex, we performed a genome-wide association study followed by replication in two independent cohorts. We identified one SNP (rs6116869) that replicated in both cohorts and had genome-wide significant association (P(combined) = 3.2 × 10(-8)). Furthermore, a metaanalysis of imputed SNPs in this genomic region identified a more significantly associated SNP (rs238295; P = 6.5 × 10(-9)) that was in strong linkage disequilibrium with rs6116869. These SNPs are located within 4 kb of the 5' UTR of GPCPD1, glycerophosphocholine phosphodiesterase GDE1 homolog (Saccharomyces cerevisiae), which in humans, is more highly expressed in occipital cortex compared with the remainder of cortex than 99.9% of genes genome-wide. Based on these findings, we conclude that this common genetic variation contributes to the proportional area of human visual cortex. We suggest that identifying genes that contribute to normal cortical architecture provides a first step to understanding genetic mechanisms that underlie visual perception.

Hierarchical temporal processing deficit model of reality distortion and psychoses

We posit in this article that hierarchical temporal processing deficit is the underlying basis of reality distortion and psychoses. Schizophrenia is a prototypical reality distortion disorder in which the patient manifests with auditory hallucinations, delusions, disorganized speech and thinking, cognitive impairment, avolition and social and occupational dysfunction. Reality distortion can be present in many other disorders including bipolar disorder, major depression and even dementia. Conceptually, schizophrenia is a heterogeneous entity likely to be because of numerous causes similar to dementia. Although no single symptom or set of symptoms is pathognomonic, a cardinal feature in all patients with schizophrenia is chronic distortion of reality. The model that we have proposed accounts for the varied manifestations of reality distortion including hallucinations and delusions. In this paper we consider the implications of this model for the underlying biology of psychoses and also for the neurobiology of schizophrenia and suggest potential targets to consider for the etiology and pathophysiology of reality distortion, especially in the context of schizophrenia.

Duane syndrome in the setting of chromosomal duplications

PURPOSE

To describe the clinical findings in 3 patients with Duane syndrome and 3 different chromosomal duplications that may indicate the location of genes involved in the pathogenesis of this ocular motility disorder.

DESIGN

Observational case series.

METHODS

setting: Clinical practice. patient or study population: Three patients with Duane syndrome and chromosomal duplications from the clinical practice of 1 of the authors. observation procedures: Chart review and retrieval of clinical data and results of pertinent clinical tests, in this case chromosomal studies. main outcome measure: Reporting of details of clinical findings and duplicated chromosomal regions.

RESULTS

Two patients had unilateral type I Duane syndrome and 1 had bilateral type I Duane syndrome. Two had cognitive delay, and all 3 had other systemic abnormalities, including a variety of congenital malformations. The chromosomal abnormalities that were detected using microarray analysis were 2q13(RP11-20G1,RP11-461N11) × 3, 10q24.2q26.3(101,532,585-135,284, 169) × 3, 20q13.12(44,796,613-44,945, 818) × 3, and 22q11.1q11.22(RP11-701M12, RP11-71G19) × 3.

CONCLUSIONS

Patients with Duane syndrome and associated congenital malformations or developmental delay should be evaluated for the presence of underlying chromosomal duplications. The regions of chromosomes 2, 10, and 22 that we report may harbor genes involved in the pathogenesis of Duane syndrome.

Human brain evolution: harnessing the genomics (r)evolution to link genes, cognition, and behavior

The evolution of the human brain has resulted in numerous specialized features including higher cognitive processes such as language. Knowledge of whole-genome sequence and structural variation via high-throughput sequencing technology provides an unprecedented opportunity to view human evolution at high resolution. However, phenotype discovery is a critical component of these endeavors and the use of nontraditional model organisms will also be critical for piecing together a complete picture. Ultimately, the union of developmental studies of the brain with studies of unique phenotypes in a myriad of species will result in a more thorough model of the groundwork the human brain was built upon. Furthermore, these integrative approaches should provide important insights into human diseases.

Disturbed Wnt Signalling due to a Mutation in CCDC88C Causes an Autosomal Recessive Non-Syndromic Hydrocephalus with Medial Diverticulum

The etiology of non-syndromic hydrocephalus is poorly understood. Via positional cloning in a consanguineous family with autosomal recessive hydrocephalus we have now identified a homozygous splice site mutation in the CCDC88C gene as a novel cause of a complex hydrocephalic brain malformation. The only living patient showed normal psychomotor development at the age of 3 years and 3 months and her deceased aunt, who was assumed to suffer from the same condition, had mild mental retardation. The mutation in the affected patients, a homozygous substitution in the donor splice site of intron 29, resulted in a shorter transcript due to exclusion of exon 29 and loss of functional protein, as shown by Western blotting (p.S1591HfsX7). In normal human tissue panels, we found CCDC88C ubiquitously expressed, but most prominently in the fetal brain, especially in pons and cerebellum, while expression in the adult brain appeared to be restricted to cortex and medulla oblongata. CCDC88C encodes DAPLE (HkRP2), a Hook-related protein with a binding domain for the central Wnt signalling pathway protein Dishevelled. Targeted quantitative RT-PCR and expression profiling of 84 genes from the Wnt signalling pathway in peripheral blood from the index patient and her healthy mother revealed increased mRNA levels of CCDC88C indicating transcriptional upregulation. Due to loss of CCDC88C function β-catenin (CTNNB1) and the downstream target LEF1 showed increased mRNA levels in the patient, but many genes from the Wnt pathway and transcriptional target genes showed reduced expression, which might be explained by a complex negative feedback loop. We have thus identified a further essential component of the Wnt signalling pathway in human brain development.

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.

Heterozygous mutations in SIX3 and SHH are associated with schizencephaly and further expand the clinical spectrum of holoprosencephaly

Schizencephaly (SCH) is a clinically and etiologically heterogeneous cerebral malformation presenting as unilateral or bilateral hemispheric cleft with direct connection between the inner and outer liquor spaces. The SCH cleft is usually lined by gray matter, which appears polymicrogyric implying an associated impairment of neuronal migration. The majority of SCH patients are sporadic, but familial SCH has been described. An initial report of heterozygous mutations in the homeobox gene EMX2 could not be confirmed in 52 patients investigated in this study in agreement with two independent SCH patient cohorts published previously. SCH frequently occurs with additional cerebral malformations like hypoplasia or aplasia of the septum pellucidum or optic nerve, suggesting the involvement of genes important for the establishment of midline forebrain structures. We therefore considered holoprosencephaly (HPE)-associated genes as potential SCH candidates and report for the first time heterozygous mutations in SIX3 and SHH in a total of three unrelated patients and one fetus with SCH; one of them without obvious associated malformations of midline forebrain structures. Three of these mutations have previously been reported in independent patients with HPE. SIX3 acts directly upstream of SHH, and the SHH pathway is a key regulator of ventral forebrain patterning. Our data indicate that in a subset of patients SCH may develop as one aspect of a more complex malformation of the ventral forebrain, directly result from mutations in the SHH pathway and hence be considered as yet another feature of the broad phenotypic spectrum of holoprosencephaly.

New trends in neuronal migration disorders

Neuronal migration disorders are an heterogeneous group of disorders of nervous system development and they are considered to be one of the most significant causes of neurological and developmental disabilities and epileptic seizures in childhood. In the last ten years, molecular biologic and genetic investigations have widely increased our knowledge about the regulation of neuronal migration during development. One of the most frequent disorders is lissencephaly. It is characterized by a paucity of normal gyri and sulci resulting in a "smooth brain". There are two pathologic subtypes: classical and cobblestone. Classical lissencephaly is caused by an arrest of neuronal migration whereas cobblestone lissencephaly caused by overmigration. Heterotopia is another important neuronal migration disorder. It is characterized by a cluster of disorganized neurons in abnormal locations and it is divided into three main groups: periventricular nodular heterotopia, subcortical heterotopia and marginal glioneural heterotopia. Polymicrogyria develops at the final stages of neuronal migration, in the earliest phases of cortical organization; bilateral frontoparietal form is characterized by bilateral, symmetric polymicrogyria in the frontoparietal regions. Bilateral perisylvian polymicrogyria causes a clinical syndrome which manifests itself in the form of mild mental retardation, epilepsy and pseudobulbar palsy. Schizencephaly is another important neuronal migration disorder whose clinical characteristics are extremely variable. This review reports the main clinical and pathophysiological aspects of these disorders paying particular attention to the recent advances in molecular genetics.

Maternal tetrahydrobiopterin deficiency: the course of two pregnancies and follow-up of two children in a mother with 6-pyruvoyl-tetrahydropterin synthase deficiency

No reports are available about the course of pregnancies in women with tetrahydrobiopterin (BH(4)) deficiencies or the effects of treatment with BH(4), L-dopa/carbidopa and 5-hydroxytryptophan (5-OHTrp) on fetal development. We present for the first time the case of a mother with late-diagnosed mild form of 6-pyruvoyl-tetrahydropterin synthase (PTPS) deficiency, the course of her two subsequent pregnancies and clinical evaluation with follow-up of two offspring. In both pregnancies neurotransmitter precursors, as well as BH(4) dosages were increased proportionally to the mother's weight gain. To prevent maternal phenylketonuria (MPKU) syndrome, special attention was paid to increasing BH(4) dosages. Both pregnancies were complicated by threatened premature labour, by the mother's nicotinism and additionally, in the first pregnancy, by gestational diabetes mellitus and vaginitis. The first child was born in the 31st week of pregnancy with the symptoms of moderate intrauterine growth retardation (IUGR) and brain malformation in the form of right sided closed-lip schizencephaly with absence of septum pellucidum. Although the girl demonstrates mild left-sided hemiparesis, her psychological development at the age of 8 years is above average. The second child was born in the 37th week of pregnancy without brain anomalies and at the age of 5 years his psychomotor development is appropriate for the age. As the cause of brain malformations resulting in physical impairment in the first child is unknown, more data are essential to verify conclusions about the influence of the mother's BH(4) deficiency and the safety of her treatment for fetal development.

The subclassification of schizencephaly and its clinical characterization

We subclassified schizencephaly based on the association with optic nerve hypoplasia (ONH) and the absence of the septum pellucidum (ASP), and then characterized their clinical presentation and prognosis. The subjects of our study consisted of 10 cases with a mean age at the final evaluation of 10 years 3 months (range, 7 months to 25 years). The subclassification of schizencephaly consisted of the septo-optic dysplasia (SOD) group (n=3), with ONH and ASP; the optic hypoplasia (OHP) group (n=2), with ONH and without ASP, and; the classical group (n=5), without ONH. The subjects with an open-lip cleft in the SOD and the classical group showed hydrocephalus, but those in the OHP group did not. The SOD and the OHP group displayed severe psychomotor retardation regardless of the cleft morphology, but in the classical group, the subjects with an open-lip cleft or with diffuse cortical dysplasia were severely retarded. The SOD and the OHP group displayed intractable epilepsy. In contrast, all subjects in the classical group showed good control of epilepsy. The results of our investigation show that the subclassification of schizencephaly based on the association with ONH and ASP is useful. The SOD group means early fetal brain injury which results in extended cortical dysplasia while the OHP group means severe destructive brain injury which results in cerebro-cerebellar disruption.

Prenatal diagnosis of schizencephaly with 2D-3D sonography and MRI

We report a case of schizencephaly diagnosed prenatally at 23 weeks of gestational age with two-dimensional (2D) and three-dimensional (3D) sonography and fetal brain MRI, confirmed by autopsy. The diagnostic method of choice is 2D transabdominal and transvaginal sonography, whereas additional 3D sonography and MRI may provide a better understanding of the pathology and related findings.

Schizencephaly in LEOPARD syndrome

We report on a 2-year-old boy with facial dysmorphism, multiple lentigines, and hypertrophic cardiomyopathy. Mutation analyses of the patient and his mother revealed a Y279G mutation in exon 7 of the PTPN11 gene. The presence of LEOPARD syndrome was confirmed by a genetic study and clinical phenotypes. Since age 18 months, the patient had manifested frequent seizures that were poorly controlled by multiple anticonvulsants. Neurologic examinations indicated severe developmental delay and sensorineural deafness. Brain imaging demonstrated open-lip schizencephaly in the right frontoparietal area. Central nervous system anomalies are rarely reported in this disease. To the best of our knowledge, this is the first report of LEOPARD syndrome with associated schizencephaly. Psychomotor retardation is not uncommon in LEOPARD syndrome. We advocate brain-imaging studies of patients with LEOPARD syndrome and neurologic abnormalities such as developmental delay or epilepsy.

Genetic basis in epilepsies caused by malformations of cortical development and in those with structurally normal brain

Epilepsy is the most common neurological disorder affecting young people. The etiologies are multiple and most cases are sporadic. However, some rare families with Mendelian inheritance have provided evidence of genes' important role in epilepsy. Two important but apparently different groups of disorders have been extensively studied: epilepsies associated with malformations of cortical development (MCDs) and epilepsies associated with a structurally normal brain (or with minimal abnormalities only). This review is focused on clinical and molecular aspects of focal cortical dysplasia, polymicrogyria, periventricular nodular heterotopia, subcortical band heterotopia, lissencephaly and schizencephaly as examples of MCDs. Juvenile myoclonic epilepsy, childhood absence epilepsy, some familial forms of focal epilepsy and epilepsies associated with febrile seizures are discussed as examples of epileptic conditions in (apparently) structurally normal brains.

Bilateral giant open lip schizencephaly with associated cerebral anomalies: a case report

A nine-month old boy was brought to our hospital with a complaint of growth retardation. On cerebral magnetic resonance imaging examination, giant clefts resulting in the connection of lateral ventricles with subarachnoidal spaces were detected in both cerebral hemispheres, and interpreted as bilateral giant open-lip schizencephaly. Associated anomalies were noted on cerebral magnetic resonance imaging examination. Bilateral thalami were located inferiorly. The caudate nuclei were observed but their configuration was disrupted. The other parts of the basal ganglia including globus pallidi and putamina were absent. We report a case of bilateral giant open-lip schizencephaly with accompanying basal ganglia anomalies.

Schizencephaly in infants with thrombophilia

Schizencephaly is an uncommon congenital malformation of neuronal migration characterized by a gray matter-lined cleft extending from the pial surface to the ependymal surface of the lateral ventricles. Its etiology is heterogeneous and consists of hereditary factors or destructive processes that occur during the second trimester of pregnancy. We report 2 cases with schizencephaly and thrombophilia caused by mutations of the methyltetrahydrofolate reductase and the factor V Leiden genes. Their clinical presentations included motor deficits and mild cognitive deficits.