> For the complete documentation index, see [llms.txt](https://help.bioinsight.illumina.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.bioinsight.illumina.com/emedgene/emedgene-analyze-manual/variant_page/quality_section/allele-distribution.md).
# Allele distribution
Review how sequencing reads support reference and alternate alleles.
The **Allele distribution card** of the **Quality tab** shows how sequencing reads support the reference and alternate allele.
It is available for SNVs, MNVs, indels (both nuclear and mitochondrial), and STRs.
## SNVs, MNVs, and indels
{% hint style="info" %}
The MNV variant type is supported from version 100.39.0.
{% endhint %}
{% columns %}
{% column width="41.66666666666667%" %}
{% endcolumn %}
{% column width="58.33333333333333%" %}
Allele fractions are shown as pie charts, one per sample. This gives you a quick view of variant distribution across alleles.
{% hint style="info" %}
For [MRJD](https://help.dragen.illumina.com/product-guide/dragen-v4.4/dragen-dna-pipeline/small-variant-calling/multi-region-joint-detection)-called variants, the alternate allele percentage shown in the graph comes from the `JAF` field in the DRAGEN MRJD VCF. `JAF` reports the alternate allele fraction across all paralogous regions.
{% endhint %}
{% endcolumn %}
{% endcolumns %}
## STRs
{% columns %}
{% column width="41.66666666666667%" %}
{% endcolumn %}
{% column width="58.33333333333333%" %}
For STRs, the allele distribution table shows how sequencing reads support an STR variant. This helps you assess call accuracy.
The columns are `REF` and `ALT`. They represent reference and alternate allele counts.
Rows are grouped into these categories:
* **In Repeat** — Reads aligning within the repeat. Higher values improve confidence.
* **Flanking** — Reads adjacent to the repeat region.
* **Spanning** — Reads covering the entire repeat region.
{% endcolumn %}
{% endcolumns %}
---
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