MTHFR and acute lymphoblastic leukemia: Noticeably, in the elder (≥ 3.5 years) group, subjects with CT or TT genotypes for MTHFR C677T had lower risks for developing childhood ALL than those with the homozygous CC genotype (P for trend = 0.0016, OR = 0.48 and 0.22, CI = 0.28–0.80 and 0.07–0.69 for CT and TT, respectively); however, this was not the case for the younger (<3.5 years) group (Table 3).