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Calling Variants with more than one tool necessary?

sp580sp580 GermanyMember

Hello!

I am currently executing GATK's best practices pipeline. However, I am trying to decide if thereafter I should call variants using other tools, as it is suggested in this 2017's review.

I am working with mouse data (60 samples, ~20x coverage per sample) and most papers use one variant calling tool (GATK or SAM/BCFtools), except for two studies using 3 callers (GATK, SAM/BCFtools, QCALL), but they are relatively "old" (2011 & 2012).

I am looking for some help to make up my mind between the choices:

  • Only GATK
  • GATK plus SAM/BCFtools
  • GATK plus SAM/BCFtools plust Tool3

Since I have only three weeks to finish this part of the project, this decission is critical.

Looking forwards for your suggestions!

Answers

  • aazizaaziz Member
    Take my advice with a grain of salt, because I'm an inexperienced PhD student. Also, you've probably already made your decision as you asked this question a few weeks ago.

    I think choosing a tool you're most familiar with, have the most in depth knowledge with, is the most important factor. Learning all 3 tools, the ins and outs, best practices is a lot of work etc is a lot of work, so chances are you will end up half assing 2 of them anyway.

    The other aspect you haven't discussed is how to deal with the output of 3 tools, do you take only the intersecting variants (only those found in all 3 tools)? or do you take all variants? Maybe you accept variants found in 2/3 tools. Are you trying to minimise false positives, reduce false negatives, or increase variant discovery (at the cost of false positives)? etc etc.

    I have seen this approach used rarely, even though it's been recommended in several different reviews of different omics fields.

    Good luck and hope I've helped.
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