SETD2 encodes a H3K36 trimethylase and loss of function mutations (missense, nonsense and frameshift mutations) have been reported in approximately 10% of acute myeloid leukemia, and 10% of acute lymphoblastic leukemia, including acute early T cell precursor acute lymphoblastic leukemia. SETD2 mutations appear to be enriched among cases of acute leukemia with rearrangements of MLL. Coexistence of two mutations in SETD2 has been described and together with recurrent loss of function mutations suggest this gene is acts as a tumor suppressor. The presence of loss of function mutations in SETD2 has been associated with global loss of H3K36me3. In addition, the presence of SETD2 mutations may be associated with therapy resistance.