AFF1 and acute lymphoblastic leukemia: Two of the translocations examined by Fitch et al. [180] are of special interest for further study as they more frequently occur in infant B ALL (KMT2A/AFF1) and childhood B cell precursor ALL (ETV6/RUNX1) yet are predicted from the studies above to arise in different B lymphoid lineages, the former in conventional B 2-like and the latter in innate B 1-like B cell lineages.