Number of forward and reverse reads that support REF and ALT alleles
FORMAT=<ID=SB,Number=4,Type=Integer,Description="Per-sample component statistics which comprise the Fisher's Exact Test to detect strand bias.">
Strand bias is a type of sequencing bias in which one DNA strand is favored over the other, which can result in incorrect evaluation of the amount of evidence observed for one allele vs. the other. The StrandBiasBySample annotation produces read counts per allele and per strand that are used by other annotation modules (FisherStrand and StrandOddsRatio) to estimate strand bias using statistical approaches.
This annotation produces 4 values, corresponding to the number of reads that support the following (in that order):
In this example, the reference allele is supported by 23 forward reads and 30 reverse reads, the alternate allele is supported by 33 forward reads and 18 reverse reads.
GATK version 3.8-0-ge9d806836 built at 2017/07/29 01:40:22.