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Browsing by Subject "retrotransposon"

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  • Sulo, Päivi (2019)
    Retrotransposons are genetic elements with the ability to make a copy of themselves and insert the copy into a new location in a genome. Most of the retrotransposons in the human genome are not transposition competent and the remaining copies are prevented from moving by epigenetics. However, some tumors experience abnormal retrotransposon activity resulting in many copies of retrotransposons inserted into new locations. Retrotransposons can be detected from sequenced genome data by bioinformatic tools. One of them is TraFiC, a tool designed to detect somatic retrotransposon insertions from tumor samples. In this Master’s thesis, I test TraFiC with 201 colorectal cancer tumors and one colorectal adenoma and develop tools to further analyze retrotransposon insertions. These tools are TraID, a pipeline to detect transductions, insertions with flanking sequence from source elements, and InSeqR, a pipeline to recreate the inserted sequence from known insertion sites. TraFiC detected 4744 somatic insertions and TraID detected 346 somatic transductions from the tumor samples. 80 % of the detected insertions were identified as true somatic insertions based on visual examination of a subset of the calls. 87 % of insertions detected by TraFiC and 82 % of the insertions detected by TraID had their insertion breakpoints and the sequence flanking them recreated by InSeqR. The detected insertions with their sequence form a reliable and comprehensive call set that can be used to create new knowledge of somatic retrotransposon insertions in colorectal cancer.