Boccia, S.

cancer study polymorphism mthfr control genotype folate result cancer risk effect alcohol meta-analysi association interaction analysis population allele individual variant intake smoking status susceptibility reductase factor gstt 1 heterogeneity alcohol consumption table boccia neck cancer level enzyme vegetable case-control ricciardi g mthfr 677 tt fruit cyp 2e consumption folate intake carrier gstm 1 mthfr c 677t subject meta-analyse epidemiology methylenetetrahydrofolate reductase 1298c cancer cases risk factors group glutathione exposure case-control study value c 2 homozygotes intron chapter epidemiol disease frequency homozygote family history p value s-transferase smoking status health research patient folate status asian ricciardi tobacco italian population carcinogenesi folate levels estimate ratio 1298c polymorphisms