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Suggested Pipeline Configuration 5.2.7

tamsen edited this page May 9, 2018 · 4 revisions

Example Variant Calling Pipeline:

Components:

Application Function Somatic Germline Notes
forthcoming indel realignment yes yes This is slow. 2-3x slower than the whole Pisces step. You can skip it if you don't need the precision. Gets rid of a lot of false positives if the upstream aligner tends to make a lot of judgment errors.
Stitcher stitches reads yes yes reconciles pairs of reads into single consensus reads,reduces FP due to noise, reduces FN due to strand bias, only works with paired end sequencing
Pisces variant calling yes yes use -ThreadByChr for faster performance but greater memory hit. Use qsub on the cluster, works fine with UMIs or for catching variants < 0.01%, so long as the data quality supports this and Pisces is properly configured.
Q Score Recalibration Downgrade Q score for poor samples yes no Run before or after scylla. Somatic calling is quite sensitive to sample degradation, germline calling less so. Gets rid of a lot of false positives if the samples has a lot of FFPE or oxidative damage that otherwise would dominate the variant calls.
Scylla long range phasing yes yes Default configuration works well with somatic. Special germline settings: ploidy=diploid, crushvcf=true, dist=5;must load the same bam that pisces does. Ie, if Pisces acts on a stitched or re-aligned bam, then so should Scylla,Turn off upstream MNV calling by Pisces.

Settings:

https://github.com/Illumina/Pisces/wiki/Pisces-Quick-Start-5.2.7

General

5.2.10

5.2.9

5.2.7

5.2.5

5.2.0

5.1.6

5.1.3

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