De Jonge [177] studied whether common polymorphisms in genes involved in folate metabolism affect MTX sensitivity, and found that polymorphisms in the folate-related genes methylenetetrahydrofolate reductase (MTHFR 677C > T, MTHFR 1298A > C), methionine synthase reductase (MTRR 66A > G), and serine hydroxymethyl transferase (SHMT1 1420 C > T) are related to MTX resistance in pediatric patients with ALL. The gene discussed is MTHFR; the disease is acute lymphoblastic leukemia.