In analysis of our Affymetrix microarray-based gene expression profiling of 100 human AML samples carrying MLL-rearrangements/t(11q23) (n = 12), inv(16) (n = 27), t(8;21) (n = 30) or t(15;17) (n = 31), along with 9 normal bone marrow (BM) control (3 each for CD34+ hematopoietic stem/ progenitor cell, CD33+ myeloid progenitor cell, and mononuclear cell (MNC)) samples27–29, we found that ALOX5 was expressed at a significantly lower level in MLL-rearranged AML, but not in other AML subtypes, relative to the normal controls (Fig. 1a). The gene discussed is KMT2A; the disease is acute myeloid leukemia.