# STR quality metrics

The following metrics are calculated for STR variants.

## VCF Filter

* The `FILTER` value in the VCF, indicating whether a variant passed caller thresholds or failed specific checks.
* Requires DRAGEN 4.3+.

## Depth

* Coverage at the repeat locus.

## Repeat Number

* Count of repeat units.

## Repeat Length

* Base-pair length of the repeat tract.

## Confidence Intervals

* Confidence intervals for the REF and ALT alleles, showing repeat-size accuracy.
* Requires DRAGEN 4.3+.

{% hint style="warning" %}
STR loci in the *ARX* and *HOXA13* genes are always marked Low quality.
{% endhint %}


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