Largest contiguous homopolymer run of the variant allele

Category Variant Annotations

VCF Field INFO (variant-level)

Type ExperimentalAnnotation

Header info
  • INFO=

  • Overview

    Repetitive sequences such as homopolymers are difficult to map to the reference because they are associated with multiple alignment possibilities. The proximity of a long homopolymer to your variant site increases the chance that reads were mapped incorrectly in the surrounding region and lowers confidence in the call. If there is a homopolymer on either side of a site, this annotation outputs the length of its largest run.


    • This can only be computed for bi-allelic sites.
    • The calculation only looks at direct runs of the alternate allele adjacent to this position, which is not a very accurate method.
    • This is an experimental annotation. As such, it is unsupported; we do not make any guarantees that it will work properly, and you use it at your own risk.

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    GATK version 3.3-0-g37228af built at 2014/10/24 14:40:51. GTD: NA