ASXL1 and acute myeloid leukemia: ASXL1 mutations without any risk factor were classified as single-hit ASXL1+ AML; ASXL1 mutations accompanied with one of the risk factors was referred to as double-hit ASXL1+ AML; ASXL1 mutations with two or more of the risk factors were designated as triple-hit ASXL1+ AML.