Folate Intake, MTHFR Polymorphisms, and the Risk of Colorectal Cancer: A Systematic Review and Meta-Analysis

Table 4

Summary effect estimate results for the MTHFR C677T and A1298C polymorphism combinations.

Comparator genotype	Number of studies	Number of participants in case/control		Summary effect estimate	95% CI	Tests for heterogeneity
		CC/AA genotype	Comparator genotype^§
							I (%)
CC/AC	12	609/775	677/870	0.96	0.82–1.11	χ² = 7.56, df = 11 (P = 0.75)	0
CC/CC	12	609/775	180/312	0.90	0.64–1.27	χ² = 21.33, df = 11 (P = 0.03)	48
CT/AA	12	609/775	753/912	0.99	0.86–1.15	χ² = 9.63, df = 11 (P = 0.56)	0
CT/AC	12	609/775	491/678	1.06	0.79–1.44	χ² = 30.68, df = 11 (P = 0.001)	64
CT/CC	5	609/775	18/36	1.40	0.33–6.03	χ² = 7.78, df = 4 (P = 0.10)	49
TT/AA	12	609/775	311/465	0.77	0.58–1.03	χ² = 19.00, df = 11 (P = 0.06)	42
TT/AC	4	609/775	11/17	N/a
TT/CC	3	609/775	0/6	N/a

^§There was one study that did not report case control numbers for the combinations.