Explore the vast range of titles available.

Polymicrogyria (PMG) is a developmental cortical malformation characterized by an excess of small and frustrane gyration and abnormal cortical lamination. PMG frequently associates with seizures. The molecular pathomechanisms underlying PMG development are not yet understood. About 40 genes have been associated with PMG, and small copy number variations have also been described in selected patients. We recently provided evidence that epilepsy-associated structural brain lesions can be classified based on genomic DNA methylation patterns. Here, we analyzed 26 PMG patients employing array-based DNA methylation profiling on formalin-fixed paraffin-embedded material. A series of 62 well-characterized non-PMG cortical malformations (focal cortical dysplasia type 2a/b and hemimegalencephaly), temporal lobe epilepsy, and non-epilepsy autopsy controls was used as reference cohort. Unsupervised dimensionality reduction and hierarchical cluster analysis of DNA methylation profiles showed that PMG formed a distinct DNA methylation class. Copy number profiling from DNA methylation data identified a uniform duplication spanning the entire long arm of chromosome 1 in 7 out of 26 PMG patients, which was verified by additional fluorescence in situ hybridization analysis. In respective cases, about 50% of nuclei in the center of the PMG lesion were 1q triploid. No chromosomal imbalance was seen in adjacent, architecturally normal-appearing tissue indicating mosaicism. Clinically, PMG 1q patients presented with a unilateral frontal or hemispheric PMG without hemimegalencephaly, a severe form of intractable epilepsy with seizure onset in the first months of life, and severe developmental delay. Our results show that PMG can be classified among other structural brain lesions according to their DNA methylation profile. One subset of PMG with distinct clinical features exhibits a duplication of chromosomal arm 1q.

BackgroundVariants in genes belonging to the tubulin superfamily account for a heterogeneous spectrum of brain malformations referred to as tubulinopathies. Variants in TUBB2A have been reported in 10 patients with a broad spectrum of brain imaging features, ranging from a normal cortex to polymicrogyria, while one patient has been reported with progressive atrophy of the cerebellar vermis.MethodsIn order to further refine the phenotypical spectrum associated with TUBB2A, clinical and imaging features of 12 patients with pathogenic TUBB2A variants, recruited via the international network of the authors, were reviewed.ResultsWe report 12 patients with eight novel and one recurrent variants spread throughout the TUBB2A gene but encoding for amino acids clustering at the protein surface. Eleven patients (91.7%) developed seizures in early life. All patients suffered from intellectual disability, and 11 patients had severe motor developmental delay, with 4 patients (36.4 %) being non-ambulatory. The cerebral cortex was normal in five individuals and showed dysgyria of variable severity in seven patients. Associated brain malformations were less frequent in TUBB2A patients compared with other tubulinopathies. None of the patients had progressive cerebellar atrophy.ConclusionThe imaging phenotype associated with pathogenic variants in TUBB2A is highly variable, ranging from a normal cortex to extensive dysgyria with associated brain malformations. For recurrent variants, no clear genotype–phenotype correlations could be established, suggesting the role of additional modifiers.

Regulation of chromatin plays fundamental roles in the development of the brain. Haploinsufficiency of the chromatin remodeling enzyme CHD7 causes CHARGE syndrome, a genetic disorder that affects the development of the cerebellum. However, how CHD7 controls chromatin states in the cerebellum remains incompletely understood. Using conditional knockout of CHD7 in granule cell precursors in the mouse cerebellum, we find that CHD7 robustly promotes chromatin accessibility, active histone modifications, and RNA polymerase recruitment at enhancers. In vivo profiling of genome architecture reveals that CHD7 concordantly regulates epigenomic modifications associated with enhancer activation and gene expression of topologically-interacting genes. Genome and gene ontology studies show that CHD7-regulated enhancers are associated with genes that control brain tissue morphogenesis. Accordingly, conditional knockout of CHD7 triggers a striking phenotype of cerebellar polymicrogyria, which we have also found in a case of CHARGE syndrome. Finally, we uncover a CHD7-dependent switch in the preferred orientation of granule cell precursor division in the developing cerebellum, providing a potential cellular basis for the cerebellar polymicrogyria phenotype upon loss of CHD7. Collectively, our findings define epigenomic regulation by CHD7 in granule cell precursors and identify abnormal cerebellar patterning upon CHD7 depletion, with potential implications for our understanding of CHARGE syndrome. CHARGE syndrome that affects cerebellar development can be caused by haploinsufficiency of the chromatin remodeling enzyme CHD7; however the precise role of CHD7 remains unknown. Here the authors show CHD7 promotes chromatin accessibility and enhancer activity in granule cell precursors and regulates morphogenesis of the cerebellar cortex, where loss of CHD7 triggers cerebellar polymicrogyria.

Reelin (RELN) is a secreted glycoprotein essential for cerebral cortex development. In humans, recessive RELN variants cause cortical and cerebellar malformations, while heterozygous variants were associated with epilepsy, autism, and mild cortical abnormalities. However, the functional effects of RELN variants remain unknown. We identified inherited and de novo RELN missense variants in heterozygous patients with neuronal migration disorders (NMDs) as diverse as pachygyria and polymicrogyria. We investigated in culture and in the developing mouse cerebral cortex how different variants impacted RELN function. Polymicrogyria-associated variants behaved as gain-of-function, showing an enhanced ability to induce neuronal aggregation, while those linked to pachygyria behaved as loss-of-function, leading to defective neuronal aggregation/migration. The pachygyria-associated de novo heterozygous RELN variants acted as dominant-negative by preventing WT RELN secretion in culture, animal models, and patients, thereby causing dominant NMDs. We demonstrated how mutant RELN proteins in vitro and in vivo predict cortical malformation phenotypes, providing valuable insights into the pathogenesis of such disorders.

GPR56, a member of the adhesion G protein-coupled receptor family, is abundantly expressed in cells of the developing cerebral cortex, including neural progenitor cells and developing neurons. The human GPR56 gene has multiple presumptive promoters that drive the expression of the GPR56 protein in distinct patterns. Similar to coding mutations of the human GPR56 gene that may cause GPR56 dysfunction, a 15-bp homozygous deletion in the cis-regulatory element upstream of the noncoding exon 1 of GPR56 ( e1m ) leads to the cerebral cortex malformation and epilepsy. To clarify the expression profile of the e1m promoter-driven GPR56 in primate brain, we generated a transgenic marmoset line in which EGFP is expressed under the control of the human minimal e1m promoter. In contrast to the endogenous GPR56 protein, which is highly enriched in the ventricular zone of the cerebral cortex, EGFP is mostly expressed in developing neurons in the transgenic fetal brain. Furthermore, EGFP is predominantly expressed in GABAergic neurons, whereas the total GPR56 protein is evenly expressed in both GABAergic and glutamatergic neurons, suggesting the GABAergic neuron-preferential activity of the minimal e1m promoter. These results indicate a possible pathogenic role for GABAergic neuron in the cerebral cortex of patients with GPR56 mutations.

This case study highlights the application of seizure fingerprint analysis in the source‐space of stereo‐EEG (SEEG) data to accurately localize the epileptogenic zone (EZ) in patients with complex cortical malformations. A 25‐year‐old female with extensive bilateral perisylvian polymicrogyria (PMG) presented with intractable focal seizures. The source‐level analysis performed in Brainstorm using the sLORETA imaging algorithm subsequently showed EZ fingerprint analysis. The patient underwent MR‐guided laser interstitial thermal therapy (LITT), targeting the identified EZ, resulting in postoperative seizure freedom with minimal complications. Extending the analysis from the sensor‐space to the source‐space could further enhance surgical planning and improve outcomes in complex epilepsy cases.

Polymicrogyria (PMG) is a multifaceted neurological disorder caused by abnormal cortical folding, mostly in children. It commonly results in developmental delays, seizures, and motor weakness. The mild features of PMG in neuroimaging often make its identification difficult, even for experts. In this paper, we assess the efficacy of various advanced image preprocessing strategies on the overall performance of Convolutional Neural Network (CNN) applied for PMG diagnosis in MRI brain scans. We employ a pre-processing sequence that includes Min–Max normalization, Contrast Limited Adaptive Histogram Equalization (CLAHE), Bilateral filtering, and Canny edge detection aimed at improving the recognition of subtle features without losing essential details. The techniques can enhance the visualization of delicate structural deformities in the brain MRI images and assist in the diagnosis of neurological disorders by clinicians. Experimental results suggest that performance enhancement was achieved with all of the tested CNN architectures. ResNet-101 has exhibited the most remarkable accuracy enhancement by 10.3%. ResNet and VGG architectures delivered much greater performance improvement as compared to MobileNetV2 and DenseNet-201 models. GradCAM++ is adopted to infer the decision-making mechanism of the considered deep learning architectures. The methodology finds applications in neurological imaging and may be used to assist healthcare providers in the diagnosis of polymicrogyria. Our findings emphasize the crucial role of image pre-processing techniques in increasing the capabilities of deep learning frameworks to assist with complex tasks in medical image analysis.

AKT3, a key component of the PI3K-AKT-MTOR pathway, is highly expressed in the brain, and its activating variants cause megalencephaly and cortical malformations. In this study, we functionally verified a novel missense AKT3 variant (p.Q78R) identified in a patient with extreme megalencephaly and intractable epilepsy. We transiently transfected HEK-293T cells with the AKT WT or AKT3 Q78R and observed a significant increase of phospho-S6, a marker of mTOR complex 1 (mTORC1) activity, in AKT3 Q78R transfected cells. Furthermore, considering its application in epilepsy treatment research, we identified a small interfering RNA (siRNA) capable of reducing the mRNA levels of AKT Q78R without affecting the expression levels of AKT3 WT . Finally, the siRNA we identified specifically suppressed the AKT3 Q78R -mediated mTORC1 activity, suggesting that this allele-specific siRNA approach holds promise for ameliorating the pathological condition.

IntroductionThe megalencephaly capillary malformation polymicrogyria (MCAP syndrome) results from mosaic gain-of-function PIK3CA variants. The main clinical features are macrocephaly, somatic overgrowth, neurodevelopmental delay and brain anomalies. Alpelisib (Vijoice) is a recently FDA-approved PI3Kα-specific inhibitor for patients with PIK3CA-related overgrowth spectrum (PROS). During its development, in patients with the MCAP subgroup of PROS, there was no specific, standardised evaluation of the effect on neuro-cognitive functioning. Moreover, it remains unknown if the molecule crosses the blood-brain barrier. Our objective is to evaluate the efficacy of a 24 month treatment with alpelisib on adaptive behaviour in patients with MCAP syndrome.Methods and analysisSESAM is an industry-sponsored two-period multicentre French academic phase II trial, with a 6-month double-blind, placebo-controlled period followed by an open-label period. The primary endpoint is a ≥4-point improvement in the Vineland II Adaptive Behaviour Scale (VABS), 24 months after treatment initiation. Secondary objectives are safety, VABS improvement at 6 months, impact on the quality of life, epilepsy and hypotonia. 20 patients aged 2 to 40 years with an MCAP diagnosis and neurodevelopmental disorders of various degrees, will be followed monthly in local centres, centrally assessed (clinical, biological, neuropsychological and functional evaluation) at baseline and every 6 months. Patients will be evaluated by volumetric MRI at baseline and at 24 months. An optional lumbar puncture will be performed to investigate blood-brain barrier crossing. Inclusions were completed by April 2024, with the end of follow-up in November 2026.Given the efficacy of alpelisib in patients with PROS, if the drug crosses the blood-brain barrier, we can expect a clinical benefit for patients with neurocognitive disorders.Ethics and disseminationEthical approval was given by CPP Sud-Ouest et Outre-Mer I (reference: 2022-500197-34-01). Findings from this study will be disseminated via publication, reports and conference presentations.Trial registration number NCT05577754

Cortical gyrification is a key marker of fetal brain development and is typically assessed qualitatively on ultrasound or MRI. While previous quantitative approaches have characterized gestational trajectories in typically developing (TD) fetuses, only a few studies have investigated cortical malformations such as lissencephaly and polymicrogyria. Spectral analysis, which characterizes signals by their frequency content, has been successfully applied to study gyrification in neonates and adults but has not yet been explored prenatally. This study aimed to apply spectral analysis to routine fetal MRI to quantitatively assess cortical gyrification, characterize gestational age-related patterns in TD fetuses, and compare gyrification across TD, lissencephaly and polymicrogyria fetuses. Cerebral contours were extracted from coronal slices, transformed into polar coordinates, and analyzed using Fourier transform to derive spectral profiles including five gyrification features based on the overall spectral power: spectral density, entropy, mean frequency, variance, and skewness as well as the first twelve frequencies. Seventy-three TD fetuses and twenty-four with malformations of cortical development (10 lissencephaly, 14 polymicrogyria) were evaluated across gestation. Differences between TD, lissencephaly, or polymicrogyria fetuses were evaluated using linear mixed models and post-hoc t-tests with Benjamini–Hochberg correction. In TD fetuses, spectral features showed gestational-age–related trajectories in most features and frequencies, corresponding to the sequential folding waves. Fetuses with cortical malformations had lower spectral density and entropy ( p  ≤ 0.031), and reduced amplitudes across most of the twelve frequencies, most prominently in frequencies associated with the Sylvian fissure ( p  < 0.001) compared with TD fetuses, with significant greater reductions in lissencephaly compared with polymicrogyria. Spectral representation may capture global cortical folding as well as distinct spectral patterns, offering a robust and quantitative biomarker of fetal brain maturation and deviations in cortical development.