AFF1 and acute lymphoblastic leukemia: Acute lymphoblastic leukaemia (ALL) carrying the t(4;11)(q21;q23) or t(9;22)(q34;q11) (Philadelphia chromosome) genetic abnormalities, associated with MLL-AF4 and the BCR-ABL fusion transcripts respectively, represents a very high risk subtype of the disease (VHR-ALL).1,2