Search

The I CIC- i rearranged sarcoma was introduced into the 2021 World Health Organization (WHO) Classification of Tumours of the Central Nervous System (CNS), by homology of its soft-tissue counterpart.1 In the CNS, I CIC i fusions mainly implicate I DUX4 i or I NUTM1 i genes but non- I CIC i fusions (such as I ATXN1::DUX4 i and I ATXN1::NUTM1 i ) have been recently described.1-3 However, DNA-methylation profiling of all I CIC- i and non- I CIC- i fused CNS mesenchymal tumours showed that all cases clustered together.2 In soft tissue, it has been evidenced that whatever the fusion partner, the I CIC i translocation induces an oncogenic activation of the PEA3 family transcription factors, including ETV4.1 Consequently, ETV4 immunohistochemistry (IHC) may represent a specific biomarker for all I CIC- i rearranged sarcomas, whereas NUT immunoexpression is only observed in I CIC::NUTM1 i -fused sarcomas.1 In the CNS, the diagnosis of I CIC- i rearranged sarcoma may be challenging for neuropathologists, and a common diagnostic biomarker of all fusions may help to identify this rare tumour type. Our work is the first to evaluate the sensitivity and specificity of ETV4 in a large cohort of molecularly defined CNS tumours. ETV4 immunohistostaining is a sensitive and specific diagnostic biomarker for CIC-rearranged sarcoma of the central nervous system. [Extracted from the article]

Aim: Rosette‐forming glioneuronal tumour (RGNT) is a rare central nervous system (CNS) World Health Organization (WHO) grade 1 brain neoplasm. According to the WHO 2021, essential diagnostic criteria are a 'biphasic histomorphology with neurocytic and a glial component, and uniform neurocytes forming rosettes and/or perivascular pseudorosettes associated with synaptophysin expression' and/or DNA methylation profile of RGNT whereas 'FGFR1 mutation with co‐occurring PIK3CA and/or NF1 mutation' are desirable criteria. Material and methods: We report a series of 46 cases fulfilling the essential pathological diagnostic criteria for RGNT. FGFR1 and PIK3CA hotspot mutations were searched for by multiplexed digital PCR in all cases, whereas DNA methylation profiling and/or PIK3R1 and NF1 alterations were analysed in a subset of cases. Results: Three groups were observed. The first one included 21 intracranial midline tumours demonstrating FGFR1 mutation associated with PIK3CA or PIK3R1 (n = 19) or NF1 (n = 1) or PIK3CA and NF1 (n = 1) mutation. By DNA methylation profiling, eight cases were classified as RGNT (they demonstrated FGFR1 and PIK3CA or PIK3R1 mutations). Group 2 comprised 11 cases associated with one single FGFR1 mutation. Group 3 included six cases classified as low‐grade glioma (LGG) other than RGNT (one‐sixth showed FGFR1 mutation and one a FGFR1 and NF1 mutation) and eight cases without FGFR1 mutation. Groups 2 and 3 were enriched in lateral and spinal cases. Conclusions: We suggest adding FGFR1 mutation and intracranial midline location as essential diagnostic criteria. When DNA methylation profiling is not available, a RGNT diagnosis remains certain in cases demonstrating characteristic pathological features and FGFR1 mutation associated with either PIK3CA or PIK3R1 mutation. [ABSTRACT FROM AUTHOR]

Background: The dystonias are a heterogeneous group of hyperkinetic disorders characterized by sustained or intermittent muscle contractions that cause abnormal movements and/or postures. Although more than 200 causal genes are known, many cases of primary dystonia have no clear genetic cause. Objectives: To identify the causal gene in a consanguineous family with three siblings affected by a complex persistent generalized dystonia, generalized epilepsy, and mild intellectual disability. Methods: We performed exome sequencing in the parents and two affected siblings and characterized the expression of the identified gene by immunohistochemistry in control human and zebrafish brains. Results: We identified a novel missense variant (c.142G>A (NM_032192); p.Glu48Lys) in the protein phosphatase 1 regulatory inhibitor subunit 1B gene (PPP1R1B) that was homozygous in all three siblings and heterozygous in the parents. This gene is also known as dopamine and cAMP‐regulated neuronal phosphoprotein 32 (DARPP‐32) and has been involved in the pathophysiology of abnormal movements. The uncovered variant is absent in public databases and modifies the conserved glutamate 48 localized close to the serine 45 phosphorylation site. The PPP1R1B protein was shown to be expressed in cells and regions involved in movement control, including projection neurons of the caudate‐putamen, substantia nigra neuropil, and cerebellar Purkinje cells. The latter cells were also confirmed to be positive for PPP1R1B expression in the zebrafish brain. Conclusions: We report the association of a PPP1R1B/DARPP‐32 variant with generalized dystonia in man. It might be relevant to include the sequencing of this new gene in the diagnosis of patients with otherwise unexplained movement disorders. © 2021 International Parkinson and Movement Disorder Society [ABSTRACT FROM AUTHOR]

Objective: Within a complex systems biology perspective, we wished to assess whether hippocampi with established neuropathological features have distinct metabolome. Apparently normal hippocampi with no signs of sclerosis (noHS), were compared to hippocampal sclerosis (HS) type 1 (HS1) and/or type 2 (HS2). Hippocampus metabolome from patients with epilepsy-associated neuroepithelial tumors (EANTs), namely, gangliogliomas (GGs) and dysembryoplastic neuroepithelial tumors (DNTs), was also compared to noHS epileptiform tissue. Methods: All patients underwent standardized temporal lobectomy. We applied ¹H high-resolution magic angle spinning nuclear magnetic resonance (HRMAS NMR) spectroscopy to 48 resected human hippocampi. NMR spectra allowed quantification of 21 metabolites. Data were analyzed using multivariate analysis based on mutual information. Results: Clear distinct metabolomic profiles were observed between all studied groups. Sixteen and 18 expected metabolite levels out of 21 were significantly different for HS1 and HS2, respectively, when compared to noHS. Distinct concentration variations for glutamine, glutamate, and N-acetylaspartate (NAA) were observed between HS1 and HS2. Hippocampi from GG and DNT patients showed 7 and 11 significant differences in metabolite concentrations when compared to the same group, respectively. GG and DNT had a clear distinct metabolomic profile, notably regarding choline compounds, glutamine, glutamate, aspartate, and taurine. Lactate and acetate underwent similar variations in both groups. Significance: HRMAS NMR metabolomic analysis was able to disentangle metabolic profiles between HS, noHS, and epileptic hippocampi associated with EANT. HRMAS NMR metabolomic analysis may contribute to a better identification of abnormal biochemical processes and neuropathogenic combinations underlying mesial temporal lobe epilepsy. [ABSTRACT FROM AUTHOR]

The p120 RasGAP protein negatively regulates Ras via its GAP domain. RasGAP carries several other domains that modulate several signaling molecules such as Rho. RasGAP is also a caspase-3 substrate. One of the caspase-3-generated RasGAP fragments, corresponding to amino acids 158-455 and called fragment N2, was previously reported to specifically sensitize cancer cells to death induced by various anticancer agents. Here, we show that fragment N2 inhibits migration in vitro and that it impairs metastatic progression of breast cancer to the lung. Hence, stress-activated caspase-3 might contribute to the suppression of metastasis through the generation of fragment N2. These results indicate that the activity borne by fragment N2 has a potential therapeutic relevance to counteract the metastatic process. [ABSTRACT FROM AUTHOR]

CIC fusions have been described in two different central nervous system (CNS) tumor entities. On one hand, fusions of CIC or ATXN1 genes belonging to the same complex of transcriptional repressors, were reported in the CIC‐rearranged, sarcoma (SARC‐CIC). The diagnosis of this tumor type, which was recently added to the World Health Organization (WHO) Classification of CNS tumors, is difficult mainly because the data concerning its histopathology (as compared to its soft tissue counterpart), immunoprofile, and clinical as well as radiological characteristics are scarce in the literature. On the other hand, a recent study, based on DNA‐methylation profiling, has identified a novel high‐grade neuroepithelial tumor characterized by recurrent CIC fusions (HGNET‐CIC). The aim of this multicentric study was to characterize a cohort of 15 primary CNS tumors harboring a CIC or ATXN1 fusion in terms of clinical, radiological, histopathological, immunophenotypical, and epigenetic characteristics. According to the integrated diagnoses, 14/15 tumors corresponded to SARC‐CIC, and only one to HGNET‐CIC. The tumors showed similar clinical (mainly pediatric), radiological (mostly supratentorial, cystic, and contrast enhancing), immunophenotypical (common expression of glioneuronal markers), and genetic (similar spectrum of fusions) profiles but their histopathological appearance was clearly distinct. Moreover, we found a novel fusion transcript (CIC::EWSR1) in a SARC‐CIC. Most DNA methylation profiles using the Heidelberg Brain Tumor Classifier (v12.8) annotated the samples to the methylation class “SARC‐CIC” (9/14 tumors with available data). By using uniform manifold approximation and projection analysis, four other samples were classified as SARC‐CIC and another clustered within the methylation class of HGNET‐CIC. Our findings confirm that CNS CIC‐fused tumors do not represent a single molecular tumor entity. Further analyses are needed to characterize HGNET‐CIC in more detail. These results may help to refine the essential diagnostic criteria for SARC‐CIC and their terminology (with a suggested consensual name of sarcoma, CIC/ATXN1‐complex rearranged). [ABSTRACT FROM AUTHOR]

Diffuse midline gliomas present a particularly intricate and challenging clinical scenario. This rare case involves a patient with comutant H3F3A and FGFR diffuse midline glioma with a clinical presentation of fulminant leptomeningitis. A 22‐year‐old male presented with fatal and fulminant diffuse leptomeningitis. Next‐generation sequencing of plasma and cerebrospinal circulating tumour DNA revealed diffuse midline gliomas with H3F3A and FGFR mutations. Methylome analysis of meningeal tissue collected during autopsy confirmed the diagnosis. Liquid biopsy plays a crucial role in the diagnosis of diffuse midline gliomas, mainly those with exclusively leptomeningeal presentations. [ABSTRACT FROM AUTHOR]