Indeed, a protective role of the DHFR19 bpdel allele in adult acute lymphoblastic leukemia (ALL) patients has been reported [26], which was further potentiated when the del allele was combined with the TT677 genotype of MTHFR, previously shown in several studies to reduce the risk of ALL [27, 28]. This evidence concerns the gene MTHFR and acute lymphoblastic leukemia.