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  • vbernard
    Junior Member
    • Jul 2012
    • 6

    #1

    TopHat2 - reads removed from the analysis?

    Hello
    We analyse Solid 5500 RNA seq reads. I used tophat2 for the alignment. We first performed the analysis ONLY on 2 chr in order to have a quick reply (that's why our number of reads aligned - see below - is very low)
    We noticed some reads were "missing" at the end of the pipeline and we're wondering why.

    These are .info files
    ::::::::::::::
    left_kept_reads.info
    ::::::::::::::
    min_read_len=50
    max_read_len=50
    reads_in =25357934
    reads_out=25319876
    ::::::::::::::
    right_kept_reads.info
    ::::::::::::::
    min_read_len=35
    max_read_len=35
    reads_in =25357934
    reads_out=25283245

    and samtools flagstat done on accepted_hits.bam

    1552361 + 0 in total (QC-passed reads + QC-failed reads)
    0 + 0 duplicates
    1552361 + 0 mapped (100.00%:-nan%)
    1552361 + 0 paired in sequencing
    769043 + 0 read1
    783318 + 0 read2
    549840 + 0 properly paired (35.42%:-nan%)
    661184 + 0 with itself and mate mapped
    891177 + 0 singletons (57.41%:-nan%)
    5522 + 0 with mate mapped to a different chr
    5522 + 0 with mate mapped to a different chr (mapQ>=5)

    and 15435015 reads are in the unmapped.bam files

    --> so that we've got 15.435.015 unmapped + 1.552.361 mapped ~ 17.000.000 reads have been analysed.
    --> we had 25.357.934 + 25.357.934 reads_in to analyse ~ 50.000.000 reads were available for the analysis.

    We're wondering where are the other reads. We expected summing the number of reads in accepted + unmapped bam files would lead to the number of reads_in but it's not the cas. If you have any explanation may I ask you to help us please?
    Thanks a lot for your time
  • vbernard
    Junior Member
    • Jul 2012
    • 6

    #2
    any idea please?
    thanks

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