At the age of 15–49 the reported cure rate is approximately 75%, but falls to 52% for those aged 75 and over [173] In a similar process to that seen in VDJ recombinase activity and B ALL cure rates, the level of activity of SMH system has been demonstrated to fall dramatically in B cells with increasing patient age and this may be linked to the fall in the cure rates of DLBCL seen in older patients [174]. Here, DNAAF19 is linked to acute lymphoblastic leukemia.