Folate metabolic gene polymorphisms and childhood acute lymphoblastic leukemia: a case–control study. - Gast, A.; Bermejo, J. L.; Flohr, T.; Stanulla, M.; Burwinkel, B.; Schrappe, M.; Bartram, C. R.; Hemminki, K.; Kumar, R. (Leukemia (08876924), 2007)