Seqanswers Leaderboard Ad

Collapse

Announcement

Collapse
No announcement yet.
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • DESeq2: outlier detection problem

    Please excuse my ignorance as I am new to DESeq2 and differential gene expression analysis in general. Also please excuse the formatting of this post (this is my first post to this forum). I appreciate in advance any and all advice and guidance.

    I am attempting to conduct a paired multi-factor analysis in DESeq2 but I seem to be detecting a lot of differentially expressed genes that are pushed into siginificance due to the presence of an outlier (see attachment of plot of normalized counts). I constructed a PCA plot (attached) and removed the labeled points and re-ran the DESeq2 analysis. I then got no significant genes. I know that DESeq2 has an internal outlier detection and replacement algorithm that requires a specified (I think default is 7) replicates. I have around 200 paired samples, ~100 pre and ~100 post treatment. In accordance with the paired multi-factor DESeq2 vignette, I have structured my sample table like so:

    HTSeq_file sex condition nested
    sample1 Male pre 1
    sample1 Male post 1
    sample2 Male pre 2
    sample2 Male post 2
    sample3 Female pre 1
    sample3 Female post 1
    ... ... ... ...


    When I remove the nested column, which to my understanding is the same as removing pairing, DESeq2 calls its internal filtering and outlier replacing methods. Is the inclusion of pairing making DESeq2 think that I have no replicates? How can I keep my paired design but still take advantage of DESeq2's outlier detection?

    All comments are greatly appreciated.

    Thanks,
    Greg
    Attached Files

  • #2
    It looks like your biggest issue is samples that should just be excluded, rather than detecting per-gene outliers.

    Anyway, the outlier detection code only gets called once you have a sufficient number of samples per group. Once you have pairing you'll never hit that, so it'll never get called. I would suggest that you just remove the obviously outlier samples and see if you get more reasonable results.

    Comment


    • #3
      That's what I suspected. Thank you very much for your quick response, I appreciate the help.

      Comment

      Latest Articles

      Collapse

      • seqadmin
        Strategies for Sequencing Challenging Samples
        by seqadmin


        Despite advancements in sequencing platforms and related sample preparation technologies, certain sample types continue to present significant challenges that can compromise sequencing results. Pedro Echave, Senior Manager of the Global Business Segment at Revvity, explained that the success of a sequencing experiment ultimately depends on the amount and integrity of the nucleic acid template (RNA or DNA) obtained from a sample. “The better the quality of the nucleic acid isolated...
        03-22-2024, 06:39 AM
      • seqadmin
        Techniques and Challenges in Conservation Genomics
        by seqadmin



        The field of conservation genomics centers on applying genomics technologies in support of conservation efforts and the preservation of biodiversity. This article features interviews with two researchers who showcase their innovative work and highlight the current state and future of conservation genomics.

        Avian Conservation
        Matthew DeSaix, a recent doctoral graduate from Kristen Ruegg’s lab at The University of Colorado, shared that most of his research...
        03-08-2024, 10:41 AM

      ad_right_rmr

      Collapse

      News

      Collapse

      Topics Statistics Last Post
      Started by seqadmin, Yesterday, 06:37 PM
      0 responses
      10 views
      0 likes
      Last Post seqadmin  
      Started by seqadmin, Yesterday, 06:07 PM
      0 responses
      9 views
      0 likes
      Last Post seqadmin  
      Started by seqadmin, 03-22-2024, 10:03 AM
      0 responses
      50 views
      0 likes
      Last Post seqadmin  
      Started by seqadmin, 03-21-2024, 07:32 AM
      0 responses
      67 views
      0 likes
      Last Post seqadmin  
      Working...
      X