Table 1.

Characteristics of MTHFR Gene C677T Polymorphism Genotype Distributions in Studies Included in the Meta-Analysis

				Genotype CC/CT/TT		Allelic frequency T of 677, (%)
Author	Year	Country	Ethnicity	Case	Control	Case	Control	Mean age(case/control)	Percentage of male(case/control)	P for HWEa	ORc	Pd	χ2
Dikmen et al.	2006	Turkey	European	28/18/3	32/21/2	24.49	22.73	N/56.8	N/29	0.601	1.73	0.765	0.089
Sazci et al.	2006	Turkey	European	10/11/7	115/119/25	44.64	32.63	N/56.7	N/56	0.572	3.12	0.071	3.262
Ynte et al.	2010	Dutch	European	185b/N/22	695b/N/69	N	N	59.5/N	28/N	N	1.20	N	N
Hultdin et al.	2011	Sweden	European	21/30/8	401/306/59	38.98	27.68	54.8/55	73/60	0.928	1.88	0.009	6.876
Fang et al.	2004	China	Asian	7/10/10	40/37/19	55.56	39.06	57.4/N	59/N	0.085	2.38	0.030	4.686
Xiao et al.	2006	China	Asian	12/33/16	49/41/10	53.29	30.5	N/53	N/58	0.813	3.20	0.000	16.507
Ye et al.	2004	China	Asian	63/27/10	192/87/21	23.5	21.5	62/63	N/67	0.017	1.48	0.554	0.3497
Zhang et al.	2004	China	Asian	94/21/59	40/49/11	39.94	35.5	69.68/57.7	63/51	0.662	1.42	0.031	4.662
Zhao et al.	2001	China	Asian	28/85/88	48/87/55	64.93	51.84	60.19/60.15	62/63	0.248	1.90	0.000	13.129
Zhang et al.	2004	China	Asian	37/68/51	65/123/51	54.49	47.07	59/57	64/38	0.697	1.79	0.042	4.153
Cai et al.	2005	China	Asian	35/24/18	35/19/11	38.96	31.54	65.69/62.25	57/51	0.010	1.50	0.193	1.694
Hu et al.	2007	China	Asian	11/12/9	61/42/12	46.88	28.7	57.9/55.3	56/45	0.257	3.36	0.006	7.525
Li et al.	2003	China	Asian	145/245/113	610/824/398	46.82	44.21	58.2/59.6	63/57	0.000	1.04	0.141	2.166
Zhang et al.	2008	China	Asian	57/103/62	74/140/68	51.26	48.94	63.5/59.4	N/N	0.906	1.22	0.284	1.148
Somarajan et al.	2011	Indian	Asian	164/44/9	129/54/5	14.29	17.02	57/55.25	69/67	1.000	1.58	0.490	0.477

^aP for Hardy–Weinberg equilibrium (HWE) in control group.

^bThe number of (CC+CT).

^cOdds ratio of individual study in recessive model (TT vs. CC+CT).

^dP for allelic (T vs. C) association.

N, not available; χ², chi-square for allelic (T vs. C) association.