Characteristic combinations of structural domains that include IDRs fused to chromatin-binding domains are also observed in the family of MLL-fusion proteins, which are found in 5%–10% of acute leukemias.63 MLL1 (also known as KMT2A) is a large (3969 amino acids) histone-lysine-N-methyltransferase acting as a transcriptional regulator. The gene discussed is KMT2A; the disease is acute leukemia.