Intermediate
Technical
IVT
variant allele fraction
The proportion of sequencing reads containing a specific genetic variant compared to total reads at that position.
Full Definition
A quantitative measure expressing the percentage of DNA molecules in a sample that carry a particular genetic variant. Variant allele fraction (VAF) is calculated by dividing the number of reads containing the variant by the total number of reads at that genomic position. In cancer genomics, VAF provides insights into tumor purity, clonality, and the proportion of cancer cells harboring specific mutations. Low VAF values may indicate subclonal mutations or contamination with normal tissue.
Usage
Usage note: Use VAF abbreviation after first mention; distinguish from population allele frequencies in genetic databases.
In Context
- "The KRAS G12D mutation showed a variant allele fraction of 23%, suggesting subclonal presence." — Molecular testing report
- "Low variant allele fractions may indicate the need for tumor enrichment prior to sequencing." — Laboratory protocol
Also known as
VAF
allele fraction
mutant allele fraction
Don't confuse with
allelic frequency
mutation frequency