CEBPA mutations, described in 5–15 % of acute myeloid leukemia (AML) patients,1 can be categorized into three types: 1) CEBPA single mutation (CEBPAsm), one mutation in one allele, 2) CEBPA double mutation (CEBPAdm), an N-terminal mutation and a basic leucine zipper motif mutation, and 3) CEBPA homozygous mutation due to loss of heterozygosity. The gene discussed is CEBPA; the disease is acute myeloid leukemia.