- Risk of colorectal cancer associated with the C677T polymorphism in 5,10-methylenetetrahydrofolate reductase in Portuguese patients depends on the intake of methyl-donor nutrients. Guerreiro, C.S., Carmona, B., Gonçalves, S., Carolino, E., Fidalgo, P., Brito, M., Leitão, C.N., Cravo, M. Am. J. Clin. Nutr. (2008)