KIT mutations have been reported in more than 90% of cases of mast cytosis [2,3], 80–85% of cases of gastrointestinal stromal tumor (GIST) [4], 10–20% of cases of melanoma [5,6], and cases of acute myeloid leukemia (AML), especially in core-binding factor (CBF) leukemia [7,8,9,10,11]. The gene discussed is CEBPZ; the disease is acute myeloid leukemia.