This implies that all TP53 copies in the sample harbor the mutation, thus resembling a sample with a 100% tumor fraction, which is above the clinically relevant range of fractions of <10%.30 To determine to which degree our assay can specifically detect the mutated allele in the presence of wild-type alleles, we diluted mutant mock cfDNA in mock cfDNA derived from a wild-type TP53 cell line, and subjected this dilution series to CRISPRDx (Fig. 6A). Here, TP53 is linked to neoplasm.