Fig. 4.

The relative coverage is affected by both neoplastic cell load and the allele copy number of the amplified gene. a The allele copy number can be estimated from relative coverage. Here, the copy number (y axis) is calculated with decreasing neoplastic cell load (x axis) for a range of relative coverages. For example, a relative coverage of 10 in case of a neoplastic cell load of 30% represents an estimated copy number of 62 alleles (see dashed line). b The detection limit of the assay can be estimated based on neoplastic cell load. In this example with a relative coverage of 3.0 as a validated analytical cutoff, the minimum detectable allele copy number in the neoplastic cells is shown with decreasing neoplastic cell load