Intermediate
Technical
IVT
allelic frequency
The percentage of reads containing a specific variant at a genomic position in a sequencing sample.
Full Definition
The proportion of sequencing reads that contain a particular variant allele at a given genomic position, typically expressed as a percentage. In cancer genomics, allelic frequency helps distinguish between germline variants (expected around 50% in diploid regions) and somatic variants (which can vary widely based on tumor purity and clonality). Low allelic frequencies may indicate subclonal mutations or contamination with normal tissue.
Usage
Usage note: Often abbreviated as VAF in clinical reports; editors should ensure consistency in terminology across documents.
In Context
- "The pathogenic KRAS mutation showed an allelic frequency of 23%, suggesting it arose in a subclonal population." — Genomic testing report
- "Quality control metrics flagged variants with allelic frequencies below 5% as potentially artifactual." — Laboratory protocol
Also known as
variant allele frequency
VAF
allele frequency
Don't confuse with
allelic imbalance
loss of heterozygosity