# Key VCF Fields

The variant calling pipeline produces a hard-filtered VCF file (`*.hard-filtered.vcf.gz`). The table below summarizes the most useful fields for somatic variant interpretation.

| Metric                 | VCF Field | Description                                                                        |
| ---------------------- | --------- | ---------------------------------------------------------------------------------- |
| Allele Frequency       | `AF`      | Fraction of reads supporting the listed variant.                                   |
| Somatic Quality        | `SQ`      | Somatic quality score; higher values indicate stronger evidence.                   |
| Systematic Noise Score | `AQ`      | Low values indicate increased probability that a variant is a systematic artifact. |
| Read Depth             | `DP`      | Number of reads at the genomic position.                                           |

For complete VCF field definitions, refer to the VCF file header and the [DRAGEN Bio-IT Platform documentation](https://support.illumina.com/sequencing/sequencing_software/dragen-bio-it-platform/product_files.html).


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