CRLF2 and acute lymphoblastic leukemia: Stanulla M. et al. described a new subgroup of B-ALL, named IKZF1plus, which is defined as IKZF1 deletion co-occurring with deletion in CDKN2A or CDKN2B (only homozygous deletion), or the PAX5 or PAR1 region (P2RY8-CRLF2), in the absence of ERG deletion.