Somatic mutations of several epigenetic modulators (DNMT3A, TET2, IDH1/2) occur frequently among patients with pre-leukemia diseases such as MDS and apparently healthy individuals with clonal hematopoiesis or CHIP, an aging-related phenotype associated with increased risk of AML (21, 22, 25, 26). The gene discussed is IDH1; the disease is myelodysplastic syndrome.