NPM1 and acute myeloid leukemia: Histone methylation levels did not significantly differ between BM and PB in AML (H3K27me3; p = 0.36, H3K4me2; p = 0.37, H3K4me3; p = 0.11, data not shown), thus samples from both sources were combined for subsequent data analysis A combined heatmap with BM and PB of both AML and ALL was created along with patient features including disease lineage, age group (< 65 or > 65 years), cytogenetics, FLT3 and NPM1 mutation (Fig. 1e).