3968 results for "*geneti*"

in 93.99 milliseconds.

• Neuroblastoma tumor heterogeneity and cell plasticity (from patients)

  Two cell identities, noradrenergic and mesenchymal, have been characterized in neuroblastoma cell lines according to their epigenetic landscapes relying on specific core regulatory circuitries of transcription factors. Yet, their relationship and relative contribution in patient tumors remain to be defined. Here, we document a spontaneous plasticity between the noradrenergic and mesenchymal identities in a subset of cell lines. Strikingly, mesenchymal neuroblastoma cells revert to a noradrenergic phenotype in vivo. Consistently, tumor cells with a mesenchymal identity are detected in single-cell transcriptomic analyses of neuroblastoma tumors and PDX models. Our data also highlight neuroblastoma intra-tumor heterogeneity with the co-existence of distinct tumor populations, including sympathoblast-like and chromaffin-like cells suggesting that neuroblastoma cells arise from a common sympatho-adrenal progenitor.

  Study EGAS00001005322

• Circulating tumor cells Exome sequencing from breast cancer

  Single cell technologies allow interrogating the extent of tumor heterogeneity, providing novel insights into tumor evolution and treatment resistance mechanisms. Here, we investigated the level of genetic heterogeneity among circulating tumor cells (CTCs) at the single nucleotide variation and copy number aberration (CNA) levels and compared it to synchronous matched primary tumor/metastatic lesion from 3 metastatic breast cancer patients with triple-negative (TNBC), HER2-positive (HER2+) and estrogen-receptor-positive (ER+) tumors. Whole exome sequencing was performed on 3 synchronous bulk tumor tissue and 21 single/pooled CTC samples. When comparing bulk tissue with CTCs from the same patient, we found similar CNA profiles and the same patient-specific driver mutations for the HER2+ and TNBC tumors. Different CNA profiles and driver mutations were found for the ER+ tumor, with two distinct clones being identified in the CTCs, one harboring an activating ESR1 mutation, the other one bearing a TP53 mutation. These data suggest that tumor tissue and CTCs provide in a subset of patients complementary clinically relevant information to map tumor heterogeneity and monitor tumor evolution. Further validation is needed.

  Study EGAS00001005228

• Molecular programs of melanoma brain metastases (MBM)

  We performed paired-end whole transcriptome sequencing of fresh frozen or intraoperative brain metastases of therapeutically treated stage IV melanoma patients. In addition, we analysed the epigenetic landscape of tumors usind Illumina 850k bead chip technology.

  Study EGAS00001005976

• Interferon lambda 4 impairs viral antigen presentation and attenuates T cell responses

  Genetic variants of the interferon lambda (IFNL) gene locus are strongly associated with spontaneous and IFN treatment induced clearance of hepatitis C virus (HCV) infections. Individuals with the ancestral IFNL4-dG allele are not able to clear HCV in the acute phase and develop chronic hepatitis C (CHC) with more than 90% probability. Paradoxically, the IFNL4-dG allele encodes a fully functional IFNλ4 protein with antiviral activity against HCV and coronavirus. Here we describe a hitherto unknown effect of IFNλ4 on HCV antigen presentation. Only minor amounts of IFNλ4 are secreted, because the protein is largely retained in the endoplasmic reticulum (ER) where it induces ER stress. Stressed cells were significantly weaker activators of HCV specific CD8+ T cells. This was not due to reduced MHC I surface presentation or extracellular IFNλ4 effects, since T cell responses could be restored by exogenous loading of MHC with HCV antigens. Rather, IFNλ4 induced ER stress impaired HCV antigen processing and/or loading onto the MHC I complex. Our results provide a potential explanation for the IFNλ4 – HCV paradox.

  Study EGAS00001005396

• Philippine Ayta possess the highest level of Denisovan ancestry in the world

  Multiple lines of evidence show that modern humans interbred with archaic Denisovans. Here, we report an account of shared demographic history between Australasians and Denisovans distinctively in Island Southeast Asia. Our analyses are based on ~2.3 million genotypes from 118 ethnic groups of the Philippines including 25 diverse self-identified Negrito populations, along with high-coverage genomes of AustraloPapuans and Ayta Magbukon Negritos. We show that Ayta Magbukon possess the highest level of Denisovan ancestry in the world – ~30-40% greater than that of Australians and Papuans – consistent with an independent admixture event into Negritos from Denisovans. Together with the recently described Homo luzonensis, we suggest that there were multiple archaic species that inhabited the Philippines prior to the arrival of modern humans, and that these archaic groups may have been genetically related. Altogether, our findings unveil a complex intertwined history of modern and archaic humans in the Asia-Pacific region, where distinct Islander Denisovan populations differentially admixed with incoming Australasians across multiple locations and at various points in time.

  Study EGAS00001005407

• Adult-type Granulosa Cell Tumour of the Ovary

  A recurrent mutation in FOXL2 (c.402C>G; p.C134W) is present in over 95% of adult-type granulosa cell tumours (AGCTs). In contrast, various loss-of-function mutations in FOXL2 lead to the development of blepharophimosis, ptosis and epicanthus inversus syndrome (BPES). BPES is characterized by an eyelid malformation often accompanied with primary ovarian insufficiency but not granulosa cell tumours. Two recent studies suggest that FOXL2 C402G is a gain or change-of-function mutation with altered DNA-binding specificity. Another study proposes that FOXL2 C402G is selectively targeted for degradation inducing somatic haploinsufficiency suggesting its role as a tumour suppressor. The latter study relies on data indicative of an FOXL2 allelic imbalance in AGCTs. Here we present RNA-seq data as genetic evidence that no real allelic imbalance is observed at the transcriptomic level in AGCTs. Additionally, there is no loss of protein expression in tumours harboring the mutated allele. These data and other features of this mutation as compared to other oncogenes and tumour suppressor genes argue strongly against FOXL2 being a tumour suppressor in this context. Given the likelihood that FOXL2 C402G is oncogenic, targeting the variant protein or its downstream consequences is the most viable path forward to identifying an effective treatment for this cancer.

  Study EGAS00001005414

• Spatial concordance of DNA methylation classification in diffuse glioma

  Background: Intratumoral heterogeneity is a hallmark of diffuse gliomas. DNA methylation profiling is an emerging approach in the clinical classification of brain tumors. The goal of this study is to investigate the effects of intratumoral heterogeneity on classification confidence. Methods: We used neuronavigation to acquire 133 image-guided and spatially-separated stereotactic biopsy samples from 16 adult patients with a diffuse glioma (7 IDH-wildtype and 2 IDH-mutant glioblastoma, 6 diffuse astrocytoma, IDH-mutant and 1 oligodendroglioma, IDH-mutant and 1p19q codeleted), which we characterized using DNA methylation arrays. Samples were obtained from regions with and without abnormalities on contrast enhanced T1 weighted and fluid-attenuated inversion recovery MRI. Methylation profiles were analyzed to devise a three-dimensional reconstruction of (epi)genetic heterogeneity. Tumor purity was assessed from clonal methylation sites. Results: Molecular aberrations indicated that tumor was found outside imaging abnormalities, underlining the infiltrative nature of this tumor and the limitations of current routine imaging modalities. We demonstrate that tumor purity is highly variable between samples and explains a substantial part of apparent epigenetic spatial heterogeneity. We observed that DNA methylation subtypes are often, but not always, conserved in space taking tumor purity and prediction accuracy into account. Conclusion: Our results underscore the infiltrative nature of diffuse gliomas and suggest that DNA methylation subtypes are relatively concordant in this tumor type, although some heterogeneity exists.

  Study EGAS00001005434

• Multimodal single-cell and bulk glioma analyses

  Glioma intratumoral heterogeneity enables adaptation to challenging microenvironments and contributes to therapeutic resistance. We integrated 914 single-cell DNA methylomes, 55,284 single-cell transcriptomes, and bulk multi-omic profiles across 11 adult IDH-mutant or IDH-wild-type gliomas to delineate sources of intratumoral heterogeneity. We show that local DNA methylation disorder associates with cell-to-cell DNA methylation differences, is elevated in more aggressive tumors, links with transcriptional disruption, and is altered in environmental stress response. Glioma cells under in vitro hypoxic and irradiation stress increased local DNA methylation disorder and shifted cell states. We identified a positive association between genetic and epigenetic instability that was supported in bulk longitudinally collected DNA methylation data. Increased DNA methylation disorder associated with accelerated disease progression, and recurrently selected DNA methylation changes were enriched for environmental stress response pathways. Our work identifies an epigenetically facilitated adaptive stress response process and highlights the importance of epigenetic heterogeneity in shaping therapeutic outcomes.

  Study EGAS00001005300

• COVID19 Host Genetic Initiative

  The COVID-19 host genetics initiative is a bottom-up collaborative effort that has three main goals: 1. Provide an environment to foster the sharing of resources to facilitate COVID-19 host genetics research (e.g. protocols, questionnaires). 2. Organize analytical activities across studies to identify genetic determinants of COVID-19 susceptibility and severity. 3. Provide a platform to share the results from such activities, as well as the individual-level data where possible, to benefit the broader scientific community. Here, we release the harmonized individual-level data for the subset of individuals who participated in COVID-19 HGI. Please refer to this data dictionary: https://docs.google.com/spreadsheets/d/1whu_MjShXxbdoAJMCYxZ5C-vWOcRivwfWglTcBRNZgQ/edit#gid=470747846 Please cite both Nakanishi, T el al. J Clin Invest 2021 (PMID: 34597274) and COVID-19 Host Genetics Initiative, Nature 2021 (PMID: 34237774) when you use these data for your publications.

  Study EGAS00001005304

• Next Generation Sequencing platform for targeted Personalized Therapy of Leukemia - Acute myeloid leukemia

  The advent of high-throughput next generation sequencing (NGS) technologies that are revolutionizing genomics and transcriptomics by providing a single base resolution tool for a unified deep analysis of diseases complexity allows a fast and cost-efficient fine-scale assessment of the genetic variability hidden within cohorts of patients affected by the same leukemia. That being so, by potentially highlighting inter-individual differences that may play a role in the differential success of diverse therapeutic interventions, they promise to be crucial for selecting the most appropriate medical treatments. The project aims at the identification of novel prognostic biomarkers for acute myeloid leukemia (AML) and studied the molecular differences between aneuploid and euploid AML.

  Study EGAS00001005464