Hi,
The variant was called by MiSeq reporter and GATK2.7 UnifiedGenotyper with VAF 19% after soft-clipping the primer sequences, as also seen in BAM file got according to GATK best practice (BWA, indel realignment, base recalibration, but no dedup due to amplicon-based sequencing). But GATK 3.3 HaplotypeCaller called a single base pair deletion instead (A: 4 (1%); C: 527) :
variants-HC3.3.vcf: chr13 28592642 . C . 1356.23 . AN=2;DP=469;MQ=59.95 GT:AD:DP 0/0:469:469
variants-UG_.vcf: chr13 28592642 rs121913488 C A 1785.77 . AC=1;AF=0.500;AN=2;BaseQRankSum=-7.477;DB;DP=731;Dels=0.00;FS=0.713;HaplotypeScore=62.1894;MLEAC=1;MLEAF=0.500;MQ=60.00;MQ0=0;MQRankSum=0.522;QD=2.44;ReadPosRankSum=0.174 GT:AD:DP:GQ:PL 0/1:596,134:731:99:1814,0,11941
The variant is at the end of one amplicon of lower coverage, close to another amplicon of much higher coverage (please see attached beforeHC.png, the soft-clipped part is primer sequences). If I trim 30 bp of the primer sequence instead of soft-clipping, the variant was called with strand bias under low stringency: 8 (12%: 1+, 7-), C: 59 (6+, 53-)
chr13 28592642 rs121913488 C A 20.80 . AC=1;AF=0.500;AN=2;BaseQRankSum=-1.750;ClippingRankSum=0.250;DB;DP=20;FS=0.000;MLEAC=1;MLEAF=0.500;MQ=60.00;MQ0=0;MQRankSum=-1.950;QD=1.04;ReadPosRankSum=-1.450;SOR=1.085 GT:AD:DP:GQ:PL 0/1:15,4:19:49:49,0,354
The variant was not called at all if I trim 22, 24, 27 or 32 bp instead of 30 bp from both ends.
Why the variant was not called by HaplotypeCaller after soft-clipping primer sequences? How can I adjust anything during the HaplotypeCaller to make this variant called? Thanks!