This conclusion, in connection with the fact that other subtypes of leukemia (e.g., the ones characterised by the BCR-ABL fusion or MLL translocations) do not show clonotypic markers at birth [18,19,20,21,22], has led scientists to believe that a gene fusion alone cannot be the causative effect for the development of leukemia. The gene discussed is KMT2A; the disease is leukemia.