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  • aldenk
    Junior Member
    • Oct 2009
    • 1

    #1

    Over represesented tags at 3'UTR - Illumina RNAseq

    Hi All ,

    I'm new to RNAseq and have just recieved my libraries from the sequencer. I've used the Illumina kit to prep and set the Solexa for 75bp reads. Tophat was used to allign my reads to the reference genome. The data look, for the most part, pretty good. I'm finding new transcripts, my tags map very well to the reference genome but, I'm finding a high number of tags that map to the 3' UTRs of many genes. They really seem to be overrepresented. The only thing I can think of is that perhaps there was incomplete reverse transcription in my cDNA synthesis?

    So far I've only looked at one library so it's possible this is just an artefact but I'm lost for an explanation. Any help would be appreciated.
  • Jon_Keats
    Senior Member
    • Mar 2010
    • 279

    #2
    I'm seeing a similar issue. In my case I'm guessing it relates to unexpected RNA fragmentation during the poly-A mRNA selection before the random priming cDNA synthesis.

    Comment

    • lmf_bill
      Member
      • Jul 2008
      • 36

      #3
      It is one general status for RNA-seq data. I agree with Jon_Keats explanation "poly-A mRNA selection bias"

      Comment

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