Measurements of disease burden using mutations vs morphologic evaluation. (A) Comparison of VAF in the PB vs BM samples. Samples with <60% lymphocytes (lymphs) are indicated in green, 60% to 74% in blue, and ≥75% in red. (B) Correlation between PB and BM VAFs based on the percent PB lymphocytes (see supplemental Methods). (C) Comparison of VAFs in patient 1027, who had a high percentage of PB lymphocytes at multiple time points. (D) Comparison of the rate of change in the tumor burden in the PB vs BM. Each data point represents the slope of VAF change during decitabine treatment of an individual patient. Because the total number of variants in the founding clone was small, the slope of the founding clone was determined using the mutation with the highest copy number–adjusted VAF on day 0. (Inset) Red, variants with copy number changes; green, founding clone variants; blue, subclonal variants; (main plot) red, average rate of change in the VAF. (E) Interobserver variability in blast count estimates between hematopathologists. (F) Coefficients of variation among all PB and BM VAFs, variants in cases with <60% blood lymphocytes, 200 cell morphologic blasts counts among 3 pathologists, and bone marrow VAFs among 3 replicate libraries created from the same sample (supplemental Figure 5D). The coefficient of variation differed between the replicate library VAFs and all other samples (P < .001) and between the blood and BM VAFs vs variants in cases with <60% blood lymphocytes (P < .05, 1-way analysis of variance Kruskal-Wallis test with Dunn’s posttest comparison of all pairs).