MTHFR C677T polymorphism and colorectal cancer risk in Asians, a meta-analysis of 21 studies.
BACKGROUND
Previous studies concerning the association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and colorectal cancer risk in Asian populations generated conflicting results. A meta-analysis was therefore performed to allow a more reliable estimate of any link.


METHODS
Relevant studies concerning the association between the MTHFR C677T polymorphism and risk of colorectal cancer were included into this meta-analysis. The quality of the studies was assessed according to a predefined scale. Odds ratios (ORs) and 95% confidence intervals (CIs) were determined for this gene-disease association using fixed or random effect models according to the heterogeneity between included studies.


RESULTS
Finally, 21 studies with a total of 6692 cases and 8266 controls were included. Meta-analyses showed that there was an obvious association of the MTHFR 677T allele with decreased risk of colorectal cancer (OR = 0.91, 95%CI=0.85-0.98, P=0.011). Subgroup analyses by country further identified this association, with dietary folate as the main source of heterogeneity.


CONCLUSIONS
The MTHFR 677T allele is associated with a lower risk of colorectal cancer in Asian populations, and there is effect modification by population plasma folate.
Department of Colorectal Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China. yangzhn@yahoo.cn
Zhen
Z
Yang
Xie-Fu
XF
Zhang
Hong-Xiang
HX
Liu
Yong-Shun
YS
Hao
Chun-Lin
CL
Zhao
D000483:Alleles; D044466:Asian People / Q000235:genetics*; D015179:Colorectal Neoplasms / Q000235:genetics*; D016001:Confidence Intervals; D004032:Diet; D005492:Folic Acid / Q000097:blood; D006801:Humans; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D016017:Odds Ratio; D020641:Polymorphism, Single Nucleotide
D005492:Folic Acid; C573423:MTHFR protein, human; D042965:Methylenetetrahydrofolate Reductase (NADPH2)