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. 2015 Oct 1;6:72–84. doi: 10.1016/j.mgene.2015.08.008

Table 2.

Summary estimates for the odds ratio (OR) of MTHFR C677T in various allele/genotype contrasts, the significance level (p value) of heterogeneity test (Q test), and the I2 metric: overall analysis, and subgroup analyses.

Genetic contrast Fixed effect
OR (95% CI), p		 Random effect
OR (95% CI), p		 Heterogeneity p-value (Q test) I2 (%)
All
(75 studies)		 Allele contrast (T vs. C) 1.05 (1.02–1.07), < 0.001 1.08 (1.03–1.13), < 0.001 < 0.001 63
Dominant (TT + CT vs. CC) 1.06 (1.02–1.09), < 0.001 1.08 (1.03–1.14), 0.002 < 0.001 48
Homozygote (TT vs. CC) 1.10 (1.04–1.16), < 0.001 1.17 (1.06–1.28), 0.001 < 0.001 60
Co-dominant (CT vs. CC) 1.05 (1.01–1.08), 0.005 1.05 (1.01–1.10), 0.01 0.01 29
Recessive (CC + CT vs. TT) 1.07 (1.02–1.13), 0.002 1.12 (1.03–1.22), 0.005 < 0.001 55



Ethnicity
Asian
(37 studies)		 Allele contrast (T vs. C) 1.06 (1.02–1.11), < 0.001 1.11 (1.02–1.21), 0.01 < 0.001 75
Dominant (TT + CT vs. CC) 1.07 (1.01–1.12), 0.009 1.10 (1.00–1.20), 0.04 < 0.001 64
Homozygote (TT vs. CC) 1.15 (1.06–1.25), < 0.001 1.26 (1.06–1.51), 0.009 < 0.001 71
Co-dominant (CT vs. CC) 1.04 (0.99–1.10), 0.08 1.05 (0.97–1.14), 0.19 0.003 43
Recessive (CC + CT vs. TT) 1.12 (1.04–1.21), 0.003 1.21 (1.04–1.40), 0.01 < 0.001 65
Caucasian
(31 studies)		 Allele contrast (T vs. C) 1.03 (1.00–1.06), 0.02 1.04 (1.00–1.09), 0.04 0.04 32
Dominant (TT + CT vs. CC) 1.04 (1.00–1.08), 0.05 1.04 (1.00–1.08), 0.05 0.56 0
Homozygote (TT vs. CC) 1.06 (0.99–1.14), 0.05 1.08 (0.97–1.21), 0.12 0.007 43
Co-dominant (CT vs. CC) 1.03 (0.99–1.08), 0.12 1.03 (0.99–1.08), 0.12 0.79 0
Recessive (CC + CT vs. TT) 1.05 (0.99–1.12), 0.09 1.07 (0.96–1.19), 0.18 0.002 47
Others
(7 studies)		 Allele contrast (T vs. C) 1.10 (0.99–1.21), 0.05 1.12 (0.97–1.28), 0.09 0.11 41
Dominant (TT + CT vs. CC) 1.17 (1.02–1.33), 0.01 1.23 (0.99–1.53), 0.05 0.03 57
Homozygote (TT vs. CC) 1.14 (0.91–1.42), 0.23 1.14 (0.91–1.44), 0.22 0.40 2
Co-dominant (CT vs. CC) 1.19 (1.03–1.36), 0.01 1.24 (1.00–1.55), 0.04 0.03 55
Recessive (CC + CT vs. TT) 1.03 (0.84–1.26), 0.74 1.03 (0.84–1.27), 0.73 0.77 0



Study design
Hospital based
(34 studies)		 Allele contrast (T vs. C) 1.07 (1.03–1.12), < 0.001 1.14 (1.05–1.23), < 0.001 < 0.001 73
Dominant (TT + CT vs. CC) 1.08 (1.03–1.14), 0.001 1.14 (1.04–1.26), 0.004 < 0.001 65
Homozygote (TT vs. CC) 1.15 (1.06–1.25), < 0.001 1.27 (1.08–1.50), 0.003 < 0.001 69
Co-dominant (CT vs. CC) 1.06 (1.01–1.12), 0.02 1.10 (1.01–1.20), 0.02 < 0.001 54
Recessive (CC + CT vs. TT) 1.12 (1.04–1.21), 0.002 1.20 (1.05–1.39), 0.008 < 0.001 63
Population based
(32 studies)		 Allele contrast (T vs. C) 1.03 (1.00–1.06), 0.04 1.03 (0.98–1.09), 0.15 0.001 48
Dominant (TT + CT vs. CC) 1.04 (0.99–1.08), 0.05 1.04 (0.98–1.09), 0.12 0.13 22
Homozygote (TT vs. CC) 1.06 (0.99–1.13), 0.07 1.08 (0.96–1.21), 0.16 < 0.001 50
Co-dominant (CT vs. CC) 1.03 (0.99–1.08), 0.10 1.03 (0.99–1.08), 0.10 0.61 0
Recessive (CC + CT vs. TT) 1.04 (0.97–1.10), 0.20 1.05 (0.95–1.16), 0.27 0.003 45



Menopausal status
Pre-menopausal
(9 studies)		 Allele contrast (T vs. C) 1.01 (0.90–1.12), 0.84 1.01 (0.98–1.12), 0.84 0.68 0
Dominant (TT + CT vs. CC) 1.00 (0.87–1.17), 0.90 1.00 (0.86–1.16), 0.92 0.45 0
Homozygote (TT vs. CC) 1.01 (0.80–1.28), 0.89 1.01 (0.80–1.28), 0.89 0.63 0
Co-dominant (CT vs. CC) 1.00 (0.85–1.17), 0.99 1.01 (0.84–1.21), 0.88 0.25 20
Recessive (CC + CT vs. TT) 1.02 (0.82–1.27), 0.83 1.02 (0.81–1.27), 0.84 0.50 0
Post-menopausal
(9 studies)		 Allele contrast (T vs. C) 1.03 (0.95–1.12), 0.40 1.05 (0.92–1.20), 0.39 0.03 51
Dominant (TT + CT vs. CC) 1.08 (0.96–1.20), 0.16 1.09 (0.95–1.25), 0.20 0.22 24
Homozygote (TT vs. CC) 1.01 (0.85–1.20), 0.87 1.06 (0.77–1.45), 0.71 0.01 57
Co-dominant (CT vs. CC) 1.10 (0.98–1.23), 0.10 1.10 (0.98–1.23), 0.10 0.62 0
Recessive (CC + CT vs. TT) 0.96 (0.82–1.13), 0.68 0.99 (0.75–1.30), 0.96 0.04 48