Polymorphisms of folate pathway enzymes (methylenetetrahydrofolate reductase and thymidylate synthase) and their relationship with thymidylate synthase expression in human astrocytic tumors.

Two important polymorphisms of folate cycle enzymes, methylenetetrahydrofolate reductase (MTHFR) C677T and thymidylate synthase (TS) enhancer region (TSER) 28-bp tandem repeat, are related to risk of various types of cancer, including brain tumors, although there are few studies on this subject. A case-control study of these two polymorphisms in astrocytomas of different grades was carried out using polymerase chain reaction-restriction fragment length polymorphism, also determining the immunohistochemical expression of TS. The MTHFR 677 TT genotype was less associated with astrocytic tumors (odds ratio [OR]=0.