MTHFR rs1801133 polymorphism is associated with increased risk of B-cell precursor lymphoblastic leukaemia with recurrent genetic aberrations of fetal origin

•MTHFR rs1801133 have a population-dependent effect in ALL risk.•Most previous studies did not take into account ALL molecular subtypes.•Was performed a case-control study with a robust sample to test this effect.•MTHFR rs1801133 was associated with higher risk of ALL with in-utero origin.•The risk was increased especially for infant ALL with KMT2A-rearrangments. Childhood acute lymphoblastic leukaemia (ALL) is a heterogeneous disease associated with multiple risk factors including genetic susceptibility. Polymorphisms in folate genes have been associated with a protective effect against ALL, although some studies contradict these findings. We aimed to test whether there is an association between the MTHFR rs1801133 variant and the occurrence of B-cell precursor ALL (BCP-ALL) taking in account molecularly distinct subtypes of fetal origin. We performed a case-control genotyping study with 2067 samples, 1309 ALL and 758 controls, from children aged ≤ 15 years for MTHFR rs1801133 polymorphism. Risk associations were calculated by odds ratios estimated with unconditional logistic regression, adjusted for frequency-matched ethnic groups. Overall, MTHFR rs1801133 does not impact ALL risk in children with more than 6 years of age. A significant positive association for MTHFR rs1801133 variant was found for ALL with KMT2A-r in the dominant model (adj. OR, 1.48, 95 % CI, 1.01–2.17), while ETV6-RUNX1 and Hyperdiploid subgroups have shown a borderline effect (adj. OR, 1.33, 95 % CI, 0.99–1.78). The polymorphism MTHFR rs1801133 increased the risk of infant ALL in Brazilian population.