3913 results for "*geneti*"

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• Egypt_Genome_Project___low_coverage_whole_genome_sequencing

  All humans outside Africa are descendants of the same single exit, usually dated at 50-70 thousand years ago. However, the route taken out of Africa is still debated. The two main candidates are a northern route via Egypt and the Levant, or a southern route via Ethiopia and the Arabian Peninsula. We are generating genetic data to evaluate these two possibilities. In this study we propose to generate low-coverage sequencing data for 100 Egyptian samples.

  Study EGAS00001000480

• ERG ALTERATIONS DEFINE A NOVEL SUBTYPE OF ACUTE LYMPHOBLASTIC LEUKEMIA

  Structural chromosomal alterations are a hallmark of acute lymphoblastic leukemia (ALL) yet many patients lack an identifiable abnormality on conventional cytogenetic analysis. Here, using integrated analysis of genome-wide DNA copy number and gene expression data of 1764 childhood and adult ALL cases, including whole-genome, exome and mRNA-sequencing of 72 cases, we report a novel subtype of B-progenitor ALL (B-ALL) representing 4-13% of B-ALL cases characterized by a distinct gene expression profile, and focal deletions of ERG (ETS related gene) in 56% of cases. These cases are characterized by expression of a ERG transcript that utilizes a novel exon in intron 6 of ERG spliced to the canonical reading frame of ERG exons 7-10, encoding a 27 kDa C-terminal ERG protein that retains the ETS and transactivating domains but lacks the N-terminal pointed and regulatory domains. This protein is a competitive inhibitor of wild-type ERG and is leukemogenic in vivo. ERG-altered ALL cases have a favourable outcome despite the presence of alterations associated with poor prognosis in non-ERG ALL, such as deletions of IKZF1. These findings identify a new subtype of leukemia characterized by a novel mechanism of ETS transcription factor dysregulation in cancer.

  Study EGAS00001000514

• CPC-GENE Prostate Cancer Heterogeneity Study

  Herein we describe a molecular portrait of potentially curable, Gleason 7 and intermediate risk prostate cancer based on genome-wide CNV profiles of 96 patients, and subsequent whole-genome sequencing of 28 tumours from 10 patients, using DNA quantities that are achievable in diagnostic biopsies (50 ng). We show that Gleason 7 cancer is highly heterogeneous at the SNV, CNV, and intra-chromosomal translocation levels, and is characterized by a very low number of recurrent SNVs but significant structural variation. We identified a novel recurrent MYCL1 amplification, which was strongly associated with TP53 deletion and prognostic for biochemical recurrence in this cohort. Moreover, we identified clear evidence of divergent tumour evolution in multi focal cancer and, in 2/5 cases evaluated, multiple tumours of independent clonal origin. Taken together, these data represent the first systematic evaluation of the differential genomics of potentially curable prostate cancer, and strongly suggest that a more robust understanding of the relationship between genetic heterogeneity and clinical outcomes is required to effectively develop biomarkers of prognosis based on tumour genomics.

  Study EGAS00001000549

• Analysis of DNA methylation in normal B cells and chronic lymphocytic leukemia

  Charting differences between tumors and normal tissue is a mainstay of cancer research. However, clonal tumor expansion from complex normal tissue architectures potentially obscures cancer-specific events, including divergent epigenetic patterns. Using whole-genome bisulfite sequencing of normal B cell subsets, we observed broad epigenetic programming of selective transcription factor binding sites coincident with the degree of B cell maturation. By comparing normal B cells to malignant B cells from 268 patients with chronic lymphocytic leukemia (CLL), we showed that tumors derive largely from a continuum of maturation states reflected in normal developmental stages. Epigenetic maturation in CLL was associated with an indolent gene expression pattern and increasingly favorable clinical outcomes.As second study using these samples focued on evolution and resulting intra-tumor heterogeneity in CLL. We used 450k bead-chip arrays to study DNA methylomes in 68 chronic lymphocytic leukemia (CLL) cases, including 28 serial cases. The result establishs linked evolution of epigenetic and genetic alterations in progressive disease, revealing an important aspect of the biology of epigenetics in cancer.

  Study EGAS00001000534

• Evolution of DNA repair defects during malignant progression of low-grade gliomas after temozolomide treatment.

  Temozolomide (TMZ) increases the overall survival of patients with glioblastoma (GBM), but its role in the clinical management of diffuse low-grade gliomas (LGG) is still being defined. DNA hypermethylation of the O 6 -methylguanine-DNA methyltransferase (MGMT) promoter is associated with an improved response to TMZ treatment, while inactivation of the DNA mismatch repair (MMR) pathway is associated with therapeutic resistance and TMZ-induced mutagenesis. We previously demonstrated that TMZ treatment of LGG induces driver mutations in the RB and AKT-mTOR pathways, which may drive malignant progression to secondary GBM. To better understand the mechanisms underlying TMZ-induced mutagenesis and malignant progression, we explored the evolution of MGMT methylation and genetic alterations affecting MMR genes in a cohort of 34 treatment-naïve LGGs and their recurrences. Recurrences with TMZ-associated hypermutation had increased MGMT methylation compared to their untreated initial tumors and higher overall MGMT methylation compared to TMZ-treated non-hypermutated recurrences. A TMZ-associated mutation in one or more MMR genes was observed in five out of six TMZ-treated hypermutated recurrences. In two cases, pre-existing heterozygous deletions encompassing MGMT, or an MMR gene, were followed by TMZ-associated mutations in one of the genes of interest. These results suggest that tumor cells with methylated MGMT may undergo positive selection during TMZ treatment in the context of MMR deficiency.

  Study EGAS00001001179

• Molecular_characterization_of_invasive_lobular_carcinoma

  Invasive lobular carcinoma (ILC) is the second most common histological subtype of breast cancer accounting for 10-15% of cases. ILC differs from invasive ductal carcinoma (IDC)with respect to epidemiology, histology, and clinical presentation. Moreover, ILC is lesssensitive to chemotherapy, more frequently bilateral, and more prone to form gastrointestinal, peritoneal, and ovarian metastases than IDCs. In contrast to IDC, the prognostic value ofhistological grade (HG) in ILC is controversial. One of the three major components of histological grading (tubule formation) is missing in ILC which hinders the process of gradingin this histological subtype and results in the classification of approximately two thirds of ILC as HG 2.Over the last decade, a number of gene expression signatures have shed light onto breast cancer classification, allowing breast cancer care to become more personalized. Withrespect to the management of estrogen receptor (ER)-positive breast cancer, several gene expression signatures provide prognostic and/or predictive information beyond what is possible with current classical clinico-pathological parameters alone. Nevertheless, most studies using gene expression signature have not considered different histologic subtypesseparately. Recently, a comprehensive research program has elucidated some of the biological underpinnings of invasive lobular carcinoma. Genetic material extracted from 200 ILC tumor samples were studied using gene expression profiling and identified ILCmolecular subtypes. These proliferation-driven gene signatures of ILC appear to have prognostic significance. In particular, the Genomic Grade (GG) gene signature improved upon HG in ILC and added prognostic value to classic clinico-pathologic factors. In addition this study demonstrated that most ILC are molecularly characterized as luminal-A (~75%)followed by luminal-B (~20%) and HER2-positve tumors (~5%). Moreover, we investigated the prognostic value of known gene signatures/ gene modules in the same cohort of ILC. As a second step within the scope of this project, we aim to investigate the interactionsbetween somatic ILC tumor mutations to observed transcriptome findings. To this end, we aim to perform somatic mutation analysis for the ILC tumors for which Affymetrix gene expression profiling is available. To this end, we will use a gene screen assay, which specifically interrogates the mutational status of a few hundreds of cancer genes. We believe that this pioneering effort will be fundamental for a tailored treatment of ILC withimprovement in patients' outcome.

  Study EGAS00001000292

• A sequence-based genetic dissection of human immune cell types and implications for immune-related disease.

  The immune system is an intricate biological network mediating interactions with other organisms while preserving the integrity of our tissues. By mounting appropriate responses it protects us from a vast range of pathogens while inadvertent immune system attacks on self result in autoimmune diseases. The project aims to discover whether and to what extent the behaviour of the immune system is genetically regulated and to detect the relationships of diverse immune cells with autoimmunity. The project consists of the genetic analysis using up to ~8.2 Million variants, deriving from high density genotyping data and low pass whole genome sequencing, and quantitative levels of 95 cell types encompassing 272 immune traits, in a cohort of 1,629 individuals from four clustered Sardinian villages belonging to the SardiNIA/ProgeNIA study.

  Study EGAS00001000574

• Assessing the impact of low frequency coding variants on disease risk using the Exomechip

  Following several rounds of Genome Wide Association (GWA) scans and subsequent meta-analyses of results multiple risk loci have been identified for many common diseases. However, in most instances the implicated common variants identified so far explain only a modest fraction of the genetic risk. In parallel to our efforts to identify the causative variants in the known loci it is necessary to assess the full spectrum of sequence variants for disease risk and in particular low frequency and rare variants that have not been tested in a comprehensive way so far. To this end an international effort by investigators who have performed whole exome sequencing in circa 12,000 individuals have assembled a set of ~250,000 exonic variants of low frequency – defined as seen in at least two studies and a minimum of three individuals (non-sysnonymous) or two individuals for SNPs altering splice sites / stop codons. The SNP content from the exome studies was complemented with additional interesting SNP sets totalling 25,000 markers (GWA tag SNPs, grid of common variants, HLA, Mitochondrial, Y-chromosome etc) and were used to generate a custom iSELECT array, the exome chip. Adequately powered association studies to test low frequency variants for association to disease risk are still very expensive if conducted by whole exome sequencing. The exome chip provides a cost efficient way to undertake such an experiment and the Wellcome Trust Cases Control Consortium will be applying this approach to eight diseases, type 1 and type 2 diabetes, coronary artery disease, hypertension, multiple sclerosis, rheumatoid arthritis, bipolar, and ankylosing spondylitis. The first objective will be to generate a large set of at least 10,000 common UK controls as analysis of lower frequency variants will require large sample sizes. This includes ~6000 samples from the 1958 Birth Cohort.

  Study EGAS00001000584

• Genome-wide SNP genotyping of Central African rainforest hunter-gatherers and neighbouring agriculturalists

  The emergence of agriculture in West-Central Africa, ~5,000 years ago, profoundly modified the cultural landscape and mode of subsistence of most sub-Saharan populations. How this major innovation has impacted the genetic history of rainforest hunter-gatherers — historically referred to as “pygmies” — and agriculturalists, however, remains poorly understood. Here, we report genome-wide SNP data from eight of these populations located west-to-east of the equatorial rainforest. We find that hunter-gathering populations present up to 50% of farmer genomic ancestry, and that substantial admixture began only within the last 1,000 years. Furthermore, we show that the historical population sizes characterising these communities already differed before the introduction of agriculture. Our results suggest that the first socio-economic interactions between rainforest hunter-gatherers and farmers introduced by the spread of farming were not accompanied by immediate, extensive genetic exchanges and occurred on a backdrop of two groups already differentiated by their specialisation in two ecotopes with differing carrying capacities.

  Study EGAS00001000605

• JMML targeted sequencing (2013)

  Juvenile myelomonocytic leukemia (JMML) is a rare myelodysplastic myeloproliferative neoplasm of early childhood initiated by germline or somatic RAS-activating mutations (Chang, Dvorak et al. 2014). Clinical evolution is heterogeneous, with acute myeloid leukemia (AML) transformation in 1/3 of cases and frequent relapses after hematopoietic-stem-cell transplantation (HSCT), although some patients experience spontaneous remission (Locatelli, Nollke et al. 2005; Matsuda, Shimada et al. 2007; Takagi, Piao et al. 2013; Locatelli and Niemeyer 2015). The initiating lesion incompletely predicts outcome, suggesting the involvement of additional mutations. Genetic profiling of a large JMML cohort (n=118), including whole-exome sequencing (WES) in 30 cases, uncovered additional genetic abnormalities in 56 cases (47%). Somatic events were rare (0.38/case/Mb) and restricted to sporadic (47/78; 60%) or NF1-associated (8/8; 100%) JMML. Multiple concomitant genetic hits were identified targeting the RAS pathway in 13/78 (17%), RAC2D63V, which activates the PI3K/PDK1/AKT and the mTORC2 pathways, and a novel pathway for JMML, the polycomb repressive complex 2 (PRC2), in 26/78 (33%) of the sporadic JMML cases. Interestingly, PRC2 imbalance was recently shown to synergize with RAS activation (De Raedt, Beert et al. 2014). JMML outcome was associated to the mutational profile, suggesting a dose-dependent effect for RAS-pathway activation, distinguishing very aggressive JMML rapidly progressing to AML.

  Study EGAS00001001324