MTHFR and acute lymphoblastic leukemia: On the contrary, the TT genotype of rs1801133 and the AC genotype of rs1801131 were reported to be associated with lower overall survival in Brazilian patients with pediatric ALL [14], and the T allele of rs1801133 and the A allele of rs1801131 (MTHFR c.T677A1298 haplotype) had a lower event free survival among Caucasians [15].