Table 2.

Meta-Analysis Odds Ratios for the Relation Between Methylenetetrahydrofolate Reductase (MTHFR) 677TT Genotype and Colorectal Cancer, by Ethnic Group and Geographic Region^a

Subgroup	No. of Studies	No. of Subjects	Reference Nos.	CT vs. CC		TT vs. CC
				OR	95% CI	OR	95% CI
Ethnic groupb
White	14	13,992	32, 38, 75, 78–86, 87, 88	0.97	0.86, 1.09	0.83	0.74, 0.94
Asianc	8	5,183	33, 67–69, 71–74	0.97	0.86, 1.10	0.80	0.67, 0.96
Geographic regiond
United States	8	12,922	27–29, 32, 38, 39, 66, 85	1.01	0.94, 1.09	0.80	0.71, 0.91
Europe	10	9,842	75, 78–84, 87, 88	0.99	0.91, 1.08	0.90	0.72, 1.13
Asiac	9	5,776	33, 67–74	0.99	0.87, 1.11	0.81	0.68, 0.97

Abbreviations: CI, confidence interval; OR, odds ratio.

^aMeta-estimate P value: white—CT, P = 0.56; TT, P = 0.003; Asian—CT, P = 0.66; TT, P = 0.016; United States—CT, P = 0.78; TT, P < 0.001; Europe—CT, P = 0.77; TT, P = 0.35; Asia—CT, P = 0.80; TT, P = 0.02.

^bSix studies were excluded because they contained mixed racial/ethnic groups or insufficient numbers of studies for grouping (e.g., the study population in the study by Wang et al. (70) was 100% Indian).

^cThe study by Wang et al. (70) was not included in the Asian ethnicity analysis because the study population was 100% Indian; however, the Wang et al. (70) study was included in the Asian geographic region because India is located in Asia.

^dTwo studies (65, 86) were excluded because they did not fall within the 3 defined categories.