Others showed conflicting results, showing that patients with the TT genotype of MTHFR rs1801133 resulted in a better overall survival rate in 126 Brazilian pediatric ALL patients treated with MTX [14], and others reported that patients carrying the T allele of rs1801133 and the A allele of rs1801131 (MTHFR c.T677A1298 haplotype) had a lower event free survival [15], and T allele of MTHFR rs1801133 and C allele of MTHFR rs1801131 had higher relapse ration [16]. This evidence concerns the gene MTHFR and acute lymphoblastic leukemia.