EPO and myelodysplastic syndrome: To understand how the microenvironment is altered across CHIP and MDS, we analyzed bone marrow (BM) samples from a balanced cohort of 84 donors, including 35 age-matched Controls, 17 CHIP donors (VAF ≥ 2%), and 32 MDS patients, the majority of whom had low-risk disease and were newly diagnosed or disease-modifying treatment-naïve cases (i.e., erythropoietin or supportive care only) (Fig. 1A, and Table 1).