As for MRD monitoring using specific probes for MLL-AF4, there are only limited published observations; in a prospective study of the GIMEMA group, MRD positivity after consolidation therapy in about 25 consecutive patients with t(4;11)/MLL-AF4 positive ALL, significantly correlates with a higher cumulative incidence of leukemia relapse and an inferior OS. The gene discussed is KMT2A; the disease is acute lymphoblastic leukemia.