IDH1 and IDH2 (isocitrate dehydrogenases 1 and 2) are enzymes that catalyze the interconversion of isocitrate and alpha-ketoglutarate and appear to play an epigenetic role in histone and possibly DNA methylation. IDH1 or IDH2 mutations confer a hypermethylation phenotype in leukemia and inhibit hematopoietic stem cell differentiation [51]. Here, IDH2 is linked to leukemia.