Pineoblastoma segregates into molecular sub-groups with distinct clinico-pathologic features: a Rare Brain Tumor Consortium registry study

Pineoblastomas (PBs) are rare, aggressive pediatric brain tumors of the pineal gland with modest overall survival despite intensive therapy. We sought to define the clinical and molecular spectra of PB to inform new treatment approaches for this orphan cancer. Tumor, blood, and clinical data from 91 patients with PB or supratentorial primitive neuroectodermal tumor (sPNETs/CNS-PNETs), and 2 pineal parenchymal tumors of intermediate differentiation (PPTIDs) were collected from 29 centres in the Rare Brain Tumor Consortium. We used global DNA methylation profiling to define a core group of PB from 72/93 cases, which were delineated into five molecular sub-groups. Copy number, whole exome and targeted sequencing, and miRNA expression analyses were used to evaluate the clinico-pathologic significance of each sub-group. Tumors designated as group 1 and 2 almost exclusively exhibited deleterious homozygous loss-of-function alterations in miRNA biogenesis genes (DICER1, DROSHA, and DGCR8) in 62 and 100% of group 1 and 2 tumors, respectively. Recurrent alterations of the oncogenic MYC-miR-17/92-RB1 pathway were observed in the RB and MYC sub-group, respectively, characterized by RB1 loss with gain of miR-17/92, and recurrent gain or amplification of MYC. PB sub-groups exhibited distinct clinical features: group 1–3 arose in older children (median ages 5.2–14.0 years) and had intermediate to excellent survival (5-year OS of 68.0–100%), while Group RB and MYC PB patients were much younger (median age 1.3–1.4 years) with dismal survival (5-year OS 37.5% and 28.6%, respectively). We identified age

Overlapping cortical malformations in patients with pathogenic variants in GRIN1 and GRIN2B

Background Malformations of cortical development (MCDs) have been reported in a subset of patients with pathogenic heterozygous variants in GRIN1 or GRIN2B, genes which encode for subunits of the N-methyl-D-aspartate receptor (NMDAR). The aim of this study was to further define the phenotypic spectrum of NMDAR-related MCDs. Methods We report the clinical, radiological and molecular features of 7 new patients and review data on 18 previously reported individuals with NMDAR-related MCDs. Neuropathological findings for two individuals with heterozygous variants in GRIN1 are presented. We report the clinical and neuropathological features of one additional individual with homozygous pathogenic variants in GRIN1. Results Heterozygous variants in GRIN1 and GRIN2B were associated with overlapping severe clinical and imaging features, including global developmental delay, epilepsy, diffuse dysgyria, dysmorphic basal ganglia and hippocampi. Neuropathological examination in two fetuses with heterozygous GRIN1 variants suggests that proliferation as well as radial and tangential neuronal migration are impaired. In addition, we show that neuronal migration is also impaired by homozygous GRIN1 variants in an individual with microcephaly with simplified gyral pattern. Conclusion These findings expand our understanding of the clinical and imaging features of the ‘NMDARopathy’ spectrum and contribute to our understanding of the likely underlying pathogenic mechanisms leading to MCD in these patients. Data availability statement Data are available upon reasonable request. All data relevant to the study are included in the article or uploaded as supplementary information. Anonymised data from this study will be shared by request from any qualified investigator

De novo variants in SP9 cause a novel form of interneuronopathy characterized by intellectual disability, autism spectrum disorder, and epilepsy with variable expressivity

Purpose: Interneuronopathies are a group of neurodevelopmental disorders characterized by deficient migration and differentiation of gamma-aminobutyric acidergic interneurons resulting in a broad clinical spectrum, including autism spectrum disorders, early-onset epileptic encephalopathy, intellectual disability, and schizophrenic disorders. SP9 is a transcription factor belonging to the Krüppel-like factor and specificity protein family, the members of which harbor highly conserved DNA-binding domains. SP9 plays a central role in interneuron development and tangential migration, but it has not yet been implicated in a human neurodevelopmental disorder. Methods: Cases with SP9 variants were collected through international data-sharing networks. To address the specific impact of SP9 variants, in silico and in vitro assays were carried out. Results: De novo heterozygous variants in SP9 cause a novel form of interneuronopathy. SP9 missense variants affecting the glutamate 378 amino acid result in severe epileptic encephalopathy because of hypomorphic and neomorphic DNA-binding effects, whereas SP9 loss-of-function variants result in a milder phenotype with epilepsy, developmental delay, and autism spectrum disorder. Conclusion: De novo heterozygous SP9 variants are responsible for a neurodevelopmental disease. Interestingly, variants located in conserved DNA-binding domains of KLF/SP family transcription factors may lead to neomorphic DNA-binding functions resulting in a combination of loss- and gain-of-function effects

[Multiple cervical arterial dissections in two brothers: fibro-muscular dysplasia or connective tissue disease?]

International audienc

Re-expression de la Filamine A dans les gliomes de haut grade - Rôle clé dans le switch invasif relayé par les récepteurs chimiotactiques.

National audienc

Autophagosome maturation is impaired in Fabry disease.

Fabry disease is a lysosomal storage disorder (LSD) caused by a deficiency in alpha-galactosidase A. The disease is characterized by severe major organ involvement, but the pathologic mechanisms responsible have not been elucidated. Disruptions of autophagic processes have been reported for other LSDs, but have not yet been investigated in Fabry disease. Renal biopsies were obtained from five adult male Fabry disease patients before and after three years of enzyme replacement therapy (ERT) with agalsidase alfa. Vacuole accumulation was seen in renal biopsies from all patients compared with control biopsies. Decreases in the number of vacuoles were seen after three years of ERT primarily in renal endothelial cells and mesangial cells. Measurement of the levels of LC3, a specific autophagy marker, in cultured cells from Fabry patients revealed increased basal levels compared to cells from non-Fabry subjects and a larger increase in response to starvation than seen in non-Fabry cells. Starvation in the presence of protease inhibitors did not result in a significant increase in LC3 in Fabry cells, whereas a further increase in LC3 was observed in non-Fabry cells, an observation that is consistent with impaired autophagic flux in Fabry disease. Overexpression of LC3 mRNA in Fabry fibroblasts compared to control cells is consistent with an upregulation of autophagy. Furthermore, LC3 and p62/SQSTM1 (that binds to LC3) staining in renal tissues and in cultured fibroblasts from Fabry patients supports impairment of autophagic flux. These findings suggest that Fabry disease is linked to a deregulation of autophagy

Détection de mutations somatiques dans l’ADN circulant plasmatique par séquençage de nouvelle génération (NGS) : première étape vers une validation du concept de biopsie liquide dans le lymphome primitif du système nerveux central.

International audienceIntroductionLes lymphomes primitifs du système nerveux central (PCNSL) sont des tumeurs rares du cerveau dont le diagnostic est complexe mais essentiel pour leur prise en charge thérapeutique. Des études récentes, dans différents types de cancers, ont montré l’intérêt de l’ADN circulant plasmatique comme méthode non invasive de détection de matériel génomique tumoral. L’objectif de cette étude était de déterminer si le séquençage ciblé de l’ADN plasmatique permettait de détecter les mutations somatiques présentes dans la tumeur chez des patients atteints d’un PCNSL.Patients et méthodesNous avons constitué une cohorte rétrospective de 30 PCNSL pour lesquels nous disposions d’ADN tumoral au diagnostic. Ces ADN ont été séquencés à l’aide du PGM ® (Life technologies) en utilisant un lymphopanel de 34 gènes. Afin d’améliorer la sensibilité du séquençage de l’ADN circulant (extrait des 24 plasmas disponibles, ADNp), les mutations somatiques identifiées dans la tumeur ont été recherchées en ciblant spécifiquement les amplicons d’intérêt. RésultatsParmi les 30 échantillons tumoraux, 21 (70%) ont été classés selon l’algorithme de Hans en sous type non GC, 8 (27%) en sous type GC et 1 non classé (3%). 29 tumeurs présentaient au moins une mutation somatique, le plus souvent un variant nucléotidique non synonyme, avec une fréquence allélique (VAF) moyenne de 46% [8%-91%]. Les profils mutationnels identifiés étaient, pour la majorité d’entre eux, caractéristiques du sous type ABC, affectant principalement les voies NF-kB et du BCR : MYD88 (n=23, 77%), PIM1 (n=11, 37%), CD79B (n=10, 33%) et TNFAIP3 (n=6, 20%). Parmi les 23 tumeurs présentant une mutation de MYD88, la L265P était la plus fréquente (20 patients, 67%) et 8 présentaient une double altération de CD79B et MYD88 (toujours la L265P). L’analyse des variations du nombre de copies de gènes a montré des délétions et gains de copie pour 29 patients dont 23 cas avec des délétions de CDKN2A/2B (77%). Les 24 plasmas disponibles présentaient de l’ADN circulant (concentration moyenne = 64 ng/mL plasma) mais aucune corrélation n’a pu être établie entre le volume tumoral et la concentration d’ADNp. Treize (54%) de ces ADNp avaient au moins une mutation détectable, avec une VAF moyenne de 4% [0.1%-28%]. Nous n’avons pas observé de différence significative de survie globale entre les patients avec ou sans mutation identifiée dans l’ADN circulant (OS 27 mois vs OS 18 mois ; p=0.3). Pour 10 des 17 patients présentant la mutation L265P dans la tumeur et avec un échantillon de plasma disponible, nous avons pu retrouver cette mutation dans l’ADNp, ce qui en fait un biomarqueur circulant potentiel intéressant.ConclusionCette étude montre pour la première fois la possibilité de détecter des mutations somatiques dans l’ADN circulant plasmatique de patients atteints d’un PCNSL, constituant ainsi un outil peu invasif qui pourrait aider au diagnostic de ces pathologies. Etant donné la récurrence des mutations de MYD88, CD79B et PIM1 dans la tumeur, un test est actuellement en cours de développement pour rechercher spécifiquement ces altérations dans l’ADNp des PCNSL. Des études complémentaires permettront d’augmenter la valeur prédictive de ce nouvel outil prometteur pour la prise en charge des PCNSL

Re-expression de la Filamine A dans les gliomes de haut grade - Rôle clé dans le switch invasif relayé par les récepteurs chimiotactiques.

National audienc

Neuropathological hallmarks of fetal hydrocephalus linked to CCDC88C pathogenic variants

Abstract The prevalence of congenital hydrocephalus has been estimated at 1.1 per 1000 infants when including cases diagnosed before 1 year of age after exclusion of neural tube defects. Classification criteria are based either on CSF dynamics, pathophysiological mechanisms or associated lesions. Whereas inherited syndromic hydrocephalus has been associated with more than 100 disease-causing genes, only four genes are currently known to be linked to congenital hydrocephalus either isolated or as a major clinical feature: L1CAM, AP1S2, MPDZ and CCDC88C. In the past 10 years, pathogenic variants in CCDC88C have been documented but the neuropathology remains virtually unknown. We report the neuropathology of two foetuses from one family harbouring two novel compound heterozygous pathogenic variants in the CCDC88C gene: a maternally inherited indel in exon 22, c.3807_3809delinsACCT;p.(Gly1270Profs*53) and a paternally inherited deletion of exon 23, c.3967-?_c.4112-?;p.(Leu1323Argfs*10). Medical termination of pregnancy was performed at 18 and 23 weeks of gestation for severe bilateral ventriculomegaly. In both fetuses, brain lesions consisted of multifocal atresia-forking along the aqueduct of Sylvius and the central canal of the medulla, periventricular neuronal heterotopias and choroid plexus hydrops. The second fetus also presented lumbar myelomeningocele, left diaphragmatic hernia and bilateral renal agenesis. CCDC88C encodes the protein DAPLE which contributes to ependymal cell planar polarity by inhibiting the non-canonical Wnt signaling pathway and interacts with MPDZ and PARD3. Interestingly, heterozygous variants in PARD3 result in neural tube defects by defective tight junction formation and polarization process of the neuroepithelium. Besides, during organ formation Wnt signalling is a prerequisite for planar cell polarity pathway activation, and mutations in planar cell polarity genes lead to heart, lung and kidney malformations. Hence, candidate variants in CCDC88C should be carefully considered whether brain lesions are isolated or associated with malformations suspected to result from disorders of planar cell polarity