Driver mutations in CH are found in distinct proportions of lymphocytes, granulocytes, and monocytes. (A) The cellular composition of blood samples significantly influences VAF measurements; thus, changes in VAF are susceptible to confounding by exposure and clinical conditions influencing cell type proportions. (B) Cell proportion informed predictions of VAF using data from methylation sequencing result in more accurate predictions of clonal trajectories, reclassifying the behavior of 57.1% of clones. CHIP, clonal hematopoiesis of indeterminate potential. See Figures 1A and 2D in the article by Parker et al that begins on page 988.