Sample variant allelic frequency [NFr]

Sample VAF

Definition

The fraction of all reads in a study sample at a given genomic locus that identify the allele (variant) in question. For homozygotes it will be close to 1.0; for heterozygotes it will be close to 0.5. It can be less than 0.5 in the case of mosaics or multiple chromosome, or mixtures of tumor cells and normal cells. This measure is an attribute of the variant and applies when the method is a Next Generation Sequencing (NGS) or similar. Such methods provide many reads from the sample for each locus. To report population allelic frequency, see [LOINC: 92821-8]. Allelic frequency is usually reported as a decimal fraction for both Sample Variant Allelic Frequency and Population Allelic Frequency, although it is occasionally reported as a percent. Special care/caution should be taken when reporting and converting to a decimal fraction.

Allelic fraction; Molecular pathology; MOLPATH; Novel allelic frequency; Number fraction; Percent; Point in time; QNT; Quan; Quant; Quantitative; Random; VAF