PMCDS000ABO - samples
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ABSTRACT:
PROVIDER: EGAD00001015158 | EGA |
REPOSITORIES: EGA
Similar Datasets
Project description:Molecular characterization of 41 tumors from 17 individuals with CMMRD to gain a better understandig of mutational processes driving subsequent tumor development. The molecular characterization includes the investigation of tumor mutational load and mutational signatures.
| EGAD00001015157 | EGA
Project description:Molecular characterization of 20 tumors of 18 children with Lynch syndrome to investigate causality. This characterization includes the investigation of second hits, tumor mutational load, mutational signatures and MMR protein expression.
| EGAS00001006992 | EGA
Project description:Gene-corrected patient-specific induced pluripotent stem (iPS) cells offer a novel approach to gene therapy. Yet it is unknown whether selective pressures during prolonged culture and multiple clonal events would introduce a mutational load incompatible with therapeutic use. Here we begin to assess whether the mutational load of gene-corrected iPS cells is compatible with use in the treatment of genetic causes of retinal degenerative disease. We isolated iPS cells free of transgene sequences from a patient with gyrate atrophy caused by a point mutation in the gene encoding ornithine-δ-aminotransferase (OAT) and used homologous recombination to correct the genetic defect. Cytogenetic analysis, array comparative genomic hybridization (aCGH), and exome sequencing were performed to assess the genomic integrity of an iPS cell line after three sequential clonal events: initial reprogramming, gene targeting, and subsequent removal of a selection cassette. No abnormalities were detected following standard G-band metaphase analysis. However, aCGH and exome sequencing identified two deletions, one amplification, and nine point mutations in protein-coding regions in the initial iPS cell clone. Except for the targeted correction of the single nucleotide in the OAT locus and a single synonymous base pair change, no additional mutations or copy number variation were identified in iPS cells following the two subsequent clonal events. These findings confirm that iPS cells themselves may carry a significant mutational load at initial isolation, but that the clonal events and prolonged cultured required for correction of a genetic defect can be accomplished without a substantial increase in mutational burden. Array comparative genomic hybridization (aCGH) were performed to assess the genomic integrity of an iPS cell line after three sequential clonal events: initial reprogramming, gene targeting, and subsequent removal of a selection cassette. Human CGH 2.1M Whole-Genome Tiling v2.0D Array plus 4633 custom-designed probes which cover the gene targeting construct and the reprogramming plasmid vectors. Comparison of patient iPS cell with full skin fibroblast cells was performed on this design.
2011-03-01 | E-GEOD-26773 | biostudies-arrayexpress
Project description:Gene-corrected patient-specific induced pluripotent stem (iPS) cells offer a novel approach to gene therapy. Yet it is unknown whether selective pressures during prolonged culture and multiple clonal events would introduce a mutational load incompatible with therapeutic use. Here we begin to assess whether the mutational load of gene-corrected iPS cells is compatible with use in the treatment of genetic causes of retinal degenerative disease. We isolated iPS cells free of transgene sequences from a patient with gyrate atrophy caused by a point mutation in the gene encoding ornithine-δ-aminotransferase (OAT) and used homologous recombination to correct the genetic defect. Cytogenetic analysis, array comparative genomic hybridization (aCGH), and exome sequencing were performed to assess the genomic integrity of an iPS cell line after three sequential clonal events: initial reprogramming, gene targeting, and subsequent removal of a selection cassette. No abnormalities were detected following standard G-band metaphase analysis. However, aCGH and exome sequencing identified two deletions, one amplification, and nine point mutations in protein-coding regions in the initial iPS cell clone. Except for the targeted correction of the single nucleotide in the OAT locus and a single synonymous base pair change, no additional mutations or copy number variation were identified in iPS cells following the two subsequent clonal events. These findings confirm that iPS cells themselves may carry a significant mutational load at initial isolation, but that the clonal events and prolonged cultured required for correction of a genetic defect can be accomplished without a substantial increase in mutational burden.
2011-03-01 | GSE26773 | GEO
Project description:Pediatric acute lymphoblastic leukemia (ALL) is marked by low mutational load at initial diagnosis, which increases at relapse. To determine which processes are active in (relapsed) ALL and how they behave during disease progression before and after therapy, we performed whole genome sequencing on tumor samples of 29 multiply relapsed ALL patients. Mutational load increased upon relapse in 28 patients and every subsequent relapse in 22 patients, with UV-like damage, APOBEC activity, reactive oxygen species, thiopurine-associated damage and an unknown therapy component driving mutagenesis. Thiopurines were the most prominent source of new mutations in relapse, affecting over half of the studied patients and causing potential relapse-driving mutations in multiple patients. Mutational processes often affected patients over longer time periods, but could also occur in isolated events, suggesting the requirement of additional triggers. Our data pose mutational processes as prominent secondary drivers with an important role in ALL development and progression.
| EGAS00001007900 | EGA
Project description:Chronic sun-damaged (CSDhigh) melanoma represents 10-20% of cutaneous melanomas and is characterized by infrequent BRAF V600E mutations and high mutational load. However, the order of genetic events, or the extent of intra-tumor heterogeneity (ITH) in CSDhigh melanoma is still unknown. Ultra-deep targeted sequencing of 40 cancer-associated genes was performed in 73 in situ or invasive CMM, including 23 CSDhigh cases. In addition, we performed whole-exome and RNA sequencing on multiple regions of primary tumor and multiple in-transit metastases from one CSDhigh melanoma patient. We found no significant difference in mutation frequency in melanoma-related genes or in mutational load between in situ and invasive CSDhigh lesions while this difference was observed in CSDlow lesions. In addition, increased frequency of BRAF V600K, NF1 and TP53 mutations (P < 0.01, Fisher’s Exact Test) was found in CSDhigh melanomas. Sequencing of multiple specimens from one CSDhigh patient revealed strikingly limited ITH with > 95% shared mutations. Our results provide evidence that CSDhigh and CSDlow melanomas are distinct molecular entities that progress via different genetic routes.
2020-05-19 | GSE139362 | GEO
Project description:Constitutional mismatch repair deficiency (CMMRD), caused by bi-allelic germline variants in one of the mismatch repair (MMR) genes, is a childhood cancer predisposition syndrome that often results in the development of multiple tumors early in life. A better understanding of mutational processes driving subsequent CMMRD tumors could advance optimal treatment. Therefore, we performed a genomic characterization of 41 tumors from 17 individuals with CMMRD. Mutational patterns in these tumors were found to be influenced by multiple factors, including the affected MMR genes, tumor types and somatic polymerase proofreading mutations. Temozolomide treatment left prominent mutational signatures in two second primary hematologic malignancies. Furthermore, a novel indel signature was found in 54% of the tumors, characterized by one base pair cytosine insertions in cytosine homopolymers. In conclusion, the analysis of sequential tumors in individuals with CMMRD reveals diverse mutational patterns influenced by the underlying mutated MMR gene, tumor type and treatment history.
| EGAS00001007660 | EGA
Project description:Deep mutational scanning is a powerful method for exploring the mutational fitness landscape of proteins. Its adaptation to anti-CRISPR proteins, which are natural CRISPR-Cas inhibitors and key players in the co-evolution of microbes and phages, facilitates their characterization and optimization. Here, we developed a robust anti-CRISPR deep mutational scanning pipeline in Escherichia coli that combines synthetic gene circuits based on CRISPR interference with flow cytometry coupled sequencing and mathematical modeling. Using this pipeline, we characterized comprehensive single point mutation libraries for AcrIIA4 and AcrIIA5, two potent inhibitors of CRISPR-Cas9. The resulting mutational fitness landscapes revealed considerable mutational tolerance for both Acrs, suggesting an intrinsic redundancy with respect to Cas9 inhibitory features, and – for AcrIIA5 – indicated mutations that boost Cas9 inhibition. Subsequent in vitro characterization suggested that the observed differences in inhibitory potency between mutant inhibitors were mostly due to changes in binding affinity rather than protein expression levels. Finally, to demonstrate that our pipeline can inform Acrs-based genome editing applications, we employed a selected subset of mutant inhibitors to increase CRISPR-Cas9 target specificity by modulating Cas9 activity. Taken together, our work establishes deep mutational scanning as a powerful method for anti-CRISPR protein characterization and optimization.
2024-03-01 | GSE254101 | GEO