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EGAS00001000515-sc-20141203 - samples

ABSTRACT: This study aims to define the landscape of somatic mutations in sun exposed human skin by deep sequencing, analyse their frequency and use the data to infer the effect of mutations on proliferating cell behaviour. The frequency of each mutation will reflect the size of the clone of cells in the tissue sample. By analyzing small samples, clones with as few as 100 cells will be detectable. Allele frequency distributions for each mutation will be used to infer cell fate using published methods (Klein et al. 2010). This study will shed unprecedented light on the early clonal events that lead to the emergence of cancer.

PROVIDER: EGAD00001001090 | EGA |

REPOSITORIES: EGA

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Tumor evolution. High burden and pervasive positive selection of somatic mutations in normal human skin.

Martincorena Iñigo I Roshan Amit A Gerstung Moritz M Ellis Peter P Van Loo Peter P McLaren Stuart S Wedge David C DC Fullam Anthony A Alexandrov Ludmil B LB Tubio Jose M JM Stebbings Lucy L Menzies Andrew A Widaa Sara S Stratton Michael R MR Jones Philip H PH Campbell Peter J PJ

Science (New York, N.Y.) 20150501 6237

How somatic mutations accumulate in normal cells is central to understanding cancer development but is poorly understood. We performed ultradeep sequencing of 74 cancer genes in small (0.8 to 4.7 square millimeters) biopsies of normal skin. Across 234 biopsies of sun-exposed eyelid epidermis from four individuals, the burden of somatic mutations averaged two to six mutations per megabase per cell, similar to that seen in many cancers, and exhibited characteristic signatures of exposure to ultrav ...[more]

PMID: 25999502

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EGAS00001000603-sc-20140423 - samples

Project description:This study aims to define the landscape of somatic mutations in sun exposed human skin by deep sequencing, analyse their frequency and use the data to infer the effect of mutations on proliferating cell behaviour. The frequency of each mutation will reflect the size of the clone of cells in the tissue sample. By analyzing small samples, clones with as few as 100 cells will be detectable. Allele frequency distributions for each mutation will be used to infer cell fate using published methods (Klein et al. 2010). This study will shed unprecedented light on the early clonal events that lead to the emergence of cancer.

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4T1 RNA-Seq

Project description:Background: the transcription of tumor mutations from DNA into RNA has implications for biology, epigenetics and clinical practice. It is not clear if mutations are in general transcribed and, if so, at what proportion to the wild-type allele. Here, we examined the correlation between DNA mutation allele frequency and RNA mutation allele frequency. Methods: we sequenced the exome and transcriptome of tumor cell lines with large copy number variations, identified heterozygous single nucleotide mutations and absolute DNA copy number, and determined the corresponding DNA and RNA mutation allele fraction. Results: we found that 99% of the DNA mutations in expressed genes are expressed as RNA. Moreover, we found a high correlation between the DNA and RNA mutation allele frequency. Exceptions are mutations that cause premature termination codons and therefore activate nonsense-mediated decay. Beyond this, we did not find evidence of any wide-scale mechanism, such as allele-specific epigenetic silencing, preferentially promoting mutated or wild-type alleles. Conclusion: taken together, our data strongly suggest that genes are equally transcribed from all alleles, mutated and wild-type, and thus transcribed in proportion to their DNA allele frequency.

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Mutational Variation in Gene Expression

Project description:Transcript abundance was measured in whole-body virgin male Drosophila serrata from 41 inbred lines that had diverged through 27 generations of mutation accumulation. Pleiotropic mutations are the ultimate source of genetic variation in complex traits, including many human diseases. However, the nature and extent of mutational pleiotropy remain largely unknown. Here, we investigate the variation in 11,604 gene expression traits among 41 mutation accumulation lines of Drosophila serrata, which had diverged for 27 generations. We detected significant mutational variance in 4.6% of ESTs, but 70% of ESTs were invariant among lines, allowing us to reject a null hypothesis of phenome-wide universal pleiotropy. Mutational covariance among ESTs was detected at a frequency of only 1 in 193 random pairs of variable EST, bu t was detected among random combinations of five ESTs in 1 in 5 cases, revealing that mutational covariance among multiple ESTs was common. The observed frequency of significant multivariate covariance among random ESTs implied that a substantial number of ESTs (>70) must be pleiotropically affected by at least some mutations. We measured gene expression of male Drosophila serrata from 41 mutation accumulation lines (whole-body). Data from two replicates for each line are presented.

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