Interestingly, some MLL-r ALL patients respond more positively to AML-oriented or AML/ALL-hybrid chemotherapeutic regiments, which is attributable to the biphenotypic and early progenitor properties of MLL-r leukemias [6,56], as demonstrated by the sensitivity of MLL-r ALL blast to cytarabine in vitro [60]. The gene discussed is KMT2A; the disease is leukemia.