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Variant Discovery in High-Throughput Sequencing Data

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Developed in the Data Sciences Platform at the Broad Institute, the toolkit offers a wide variety of tools with a primary focus on variant discovery and genotyping. Its powerful processing engine and high-performance computing features make it capable of taking on projects of any size. Learn more

calculateContamination step with multi-tumor samples

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    David Benjamin

    jungmin choi Multi-sample mode in Mutect2 is a relatively new feature, so please pardon that out tutorials haven't caught up yet.  We do, however, have up-to-date documentation in our github repo: https://github.com/broadinstitute/gatk/blob/master/docs/mutect/mutect.pdf.  Your questions are answered on page 4 in the sample command line for FilterMutectCalls.

    The short answer, though, is that you must specify `--tumor-segmentation` and `--contamination-table` multiple times, once for each sample you wish to apply contamination filtering to.  Usually the best practice would be once per tumor sample, but this is not necessary.  Furthermore, it is allowable to have tumor segmentation without the contamination table and vice versa.  For example, in joint calling with three tumor samples, the following is valid.

    gatk FilterMutectCalls -V unfiltered.vcf \
       --tumor-segmentation segments1.table \
    --tumor-segmentation segments2.table \ --contamination-table contamination2.table \ --ob-priors read-orientation-model.tar.gz \ -O filtered.vcf
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    David Benjamin

    By the way, this works because the segmentation and contamination tables contain sample information, which FilterMutectCalls recognizes.  And thank you for trying out joint calling with Mutect2!

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    jungmin choi

    David Benjamin

    Thank you and great to have the latest Mutect2 documentation now.

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    jungmin choi

    David Benjamin

    I am a bit perplexed to see the results like below. The order of the samples is tumor1, normal, and tumor2 from the same patient. Is the tool genotyping the tumor automatically heterozygous (0/1) regardless of the allelic fraction (0,0)?

    1       26707938        .       G       A       .       PASS    CONTQ=93;DP=56;ECNT=1;GERMQ=56;MBQ=34,24;MFRL=160,192;MMQ=60,60;MPOS=10;NALOD=0.782;NLOD=5.80;POPAF=6.00;ROQ=64;SEQQ=61;STRANDQ=52;TLOD=12.36   GT:AD:AF:DP:F1R2:F2R1:SB        0/1:23,9:0.288:32:11,4:10,3:17,6,7,2    0/0:20,0:0.045:20:6,0:13,0:12,8,0,0     0/1:0,0:0.500:0:0,0:0,0:0,0,0,0

    Thank you!

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    David Benjamin

    jungmin choi Yes, the GT field is Mutect2 output is not meaningful.

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    jungmin choi

    David Benjamin

     

    Thanks for confirming this. I am also getting errors when I specify -bamout parameter like below. Is this expected as well?

     

    -bamout <pair>/gatk4.1_multisample/<pair>.mutect2.<chunk>.bam

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    David Benjamin

    I think we might never have tested -bamout in Mutect2's multi-sample mode, so it's quite possible.  It's not the highest priority, but it would be nice to fix and I bet it's not that hard.  What error and stack trace are you getting?

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    jungmin choi

    I am no longer reproducing the bamout errors. It must have been a syntax mistake on my side. Please disregard my question.

     

    Thanks!

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