Unconfigured Ad

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts
  • SWP
    Member
    • Nov 2010
    • 20

    mpileup SNP detection

    Hello all-

    I've got several full genomes sequenced off a HiSeq. There's good coverage (~30x). Alignments were performed with default parameters in BWA. These are Caucasian individuals.

    Variant detection was performed using mpileup, using almost exact parameters listed on the samtools page:

    samtools mpileup -uf ref.fa output.sorted.bam | bcftools view -bvcg - > var.raw.bcf

    bcftools view var.raw.bcf | vcfutils.pl varFilter -D100000 > var.flt.vcf

    Not a single indel was called, and only ~2 million SNPs. 2 million is well below the >3 million I expected.

    I was wondering if anyone who has aligned a full genome with similar depth of coverage, and called variants using mpileup and got a more reasonable variant number, would be willing to share what parameters were used?

    The raw bcf file has ~3.9 million variants.

    Any ideas/suggestions?
  • colindaven
    Senior Member
    • Oct 2008
    • 417

    #2
    That does seem like a very high coverage you are requiring (-D100000).

    Perhaps try a lower number? Mpileup is pretty good software but I agree with what you are saying.

    Comment

    • SWP
      Member
      • Nov 2010
      • 20

      #3
      The -D option is not a minimum coverage requirement, it's the highest coverage allowed...unless I completely misunderstand something about mpileup. My intention was to have no regions excluded because the coverage was too high, and since I'm a bit OCD I used 10000 as opposed to something like 300 which would probably be adequate.

      I believe I had a corrupted file and I'm running mpileup now and it appears to be working correctly.

      Comment

      Latest Articles

      Collapse

      • SEQadmin2
        Nine Things a Sample Prep Scientist Thinks About Before Sequencing
        by SEQadmin2


        I’m not a sequencing expert. I’m a purification scientist who uses NGS to evaluate workflows my group develops. With this perspective, we think about the sample first and the NGS workflow second. The sequencer is an exceptionally honest reporter, but it can only report on what you give it, so whether you get clean, interpretable data from an NGS workflow is largely determined before you begin.

        Here are nine questions we think about, in roughly the order they matter, before...
        06-18-2026, 07:11 AM
      • SEQadmin2
        From Collection to Sequencing: Why Sample Preparation and Preservation Define Sequencing Data
        by SEQadmin2


        Data variability is still an issue in sequencing technologies despite the advances in reproducibility and accuracy of these platforms. But the problem does not originate in the sequencing itself, but in the previous steps, before the sample reaches the sequencer.


        The first step is collection, followed by preservation and sample preparation for analysis. Most scientists overlook those steps, but not being careful might just be skewing the experiment’s results.
        ...
        06-02-2026, 10:05 AM

      ad_right_rmr

      Collapse

      News

      Collapse

      Topics Statistics Last Post
      Started by SEQadmin2, 06-17-2026, 06:09 AM
      0 responses
      38 views
      0 reactions
      Last Post SEQadmin2  
      Started by SEQadmin2, 06-09-2026, 11:58 AM
      0 responses
      100 views
      0 reactions
      Last Post SEQadmin2  
      Started by SEQadmin2, 06-05-2026, 10:09 AM
      0 responses
      121 views
      0 reactions
      Last Post SEQadmin2  
      Started by SEQadmin2, 06-04-2026, 08:59 AM
      0 responses
      114 views
      0 reactions
      Last Post SEQadmin2  
      Working...