Some of the genes with low mutation rates occurred exclusively, including genes with redundant functions like e.g. the histone methyltransferases, WHSC1 and MLL2. WHSC1 (also known as NSD2 or MMSET2) is associated with the prognostic unfavourable t(4;14) subgroup in multiple myeloma[44] and only very recently described in T-ALL[45,46]. Here, PRDM9 is linked to acute lymphoblastic leukemia.