Association between polymorphism of methylenetetrahydrofolate reductase (MTHFR) C677T and risk of myocardial infarction: a meta-analysis for 8,140 cases and 10,522 controls

Background and aims: The methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism has been reported to be associated with myocardial infarction (MI), but results from previous studies are conflicting. The present study aimed at investigating the association between this polymorphism and risk of MI using a meta-analysis on the published studies.

Methods: Medline, EBSCO, BIOSIS, and Cochrane Library were searched to identify eligible studies published in English before August, 2011. Data were extracted using standardized methods. The association was assessed by odds ratio (OR) with 95% confidence intervals (CI). Begg's test was used to measure publication bias.

Results: A total of 30 case-control studies containing 8,140 MI cases and 10,522 controls were involved in this meta-analysis. Overall, significant association was found between MTHFR C677T polymorphism and risk of MI when all studies pooled with fixed-effects model for TT vs. CT (OR = 1.183, 95% CI: 1.076-1.300). In the subgroup analysis, the same association was found in overall Caucasians (OR = 1.139, 95% CI: 1.007-1.288) and young/middle-aged (<50 years) Caucasians (OR = 1.275, 95% CI: 1.077-1.509). No associations were detected between MTHFR C677T and the risk of MI in elderly male or female Caucasians, East Asians, South Asians, and African-Americans.

Conclusions: Meta-analysis results suggest that the MTHFR C677T polymorphism was associated with risk of MI in young/middle-aged Caucasians. The effect of the variants on the expression levels and the possible functional role of the variants in MI should be addressed in further studies.