DOT1L (Disruptor of Telomeric silencing 1-Like) is associated with KMT2A fusion proteins (Fig. 1) in KMT2A-rearranged AML, as it interacts with many of the known fusion partner proteins of KMT2A, such as AFF1 (also known as AF4), and MLLT3 (also known as AF9). This evidence concerns the gene AFF1 and acute myeloid leukemia.