MTHFD1 and precursor B-cell acute lymphoblastic leukemia: Interestingly, a common polymorphism of MTHFD1 R653Q (MTHFD1 G1958A) in the synthetase domain impairs purine synthesis and the corresponding AA genotype is associated with a decreased risk of human B-ALL and NHL (82, 83), indicating a role of this enzyme in B cell oncogenesis.