In this context, the existence of strong linkage disequilibrium between two DHFR promoter polymorphisms (i.e., −317AG, rs408626, and the ins/del, rs70991108) [67] may account for the good prognosis we observed among DHFR DD-homozygous ALL children during the five-year follow-up. Here, DHFR is linked to acute lymphoblastic leukemia.