Putative loss of function BCOR mutations represent a substantial fraction of cytogenetically normal (CN)-AML patients, are frequently associated with DNMT3A mutations and were proposed to be associated with an inferior outcome.113 Sportoletti et al114 explored functional cooperation with a conditional mouse model mimicking AML-associated BCOR truncating mutations. The gene discussed is DNMT3A; the disease is acute myeloid leukemia.