Configurations of somatic and germ line mutations and VAF concept. (A) Possible configurations of somatic mutations (left) or germ line (right) and chromosomal abnormalities. (B) Impact of clonal configuration on VAF vs calculated clonal burden, including impact of homozygous, hemizygous, or heterozygous mutations (dotted circles show magnified representations of the illustrations in each setting as described). (C) Somatic ancestral vs secondary hits and potential clinical behavior of secondary clones as persistent, disappearing, and sweeping. Ancestral hits are the only somatic events that can occur as single hits. Secondary hits can be present only in association with the ancestral hit. Secondary mutations create a scenario in which only very few single mutant cells exist. Sweeping clones/mutations outgrow single mutant clones, and thus, their VAF may be very similar to that of founder mutations.