To test this hypothesis we assessed whether the variants of the methylene tetrahydrofolate reductase (MTHFR), methionine synthase (MTR), methionine synthase reductase (MTRR), cystathionine beta-synthase (CBS) and endothelial nitric acid synthase (eNOS, NOS3) genes, acting either independently or in conjunction with other risk factors, influenced the cognitive functioning in ALL patients.