Table 1. Study characteristics of MTR rs1805087 A2756G polymorphism included in this meta-analysis.

First author	Year	Country	Ethnicity	Source	Genotyping	Sample size of case					Sample size of control					Average age		PHWE	NOS
					methods	GG	GA	AA	MAF	Total	GG	GA	AA	MAF	Total	Case	Control
Ebrahimi	2017	Iran	Asian	HB	PCR-RFLP	13	53	34	0.395	100	6	37	57	0.245	100	NA	NA	0.999	7
Qu	2016	China	Asian	HB	real-time PCR	20	316	1481	0.098	1817	15	319	1692	0.086	2026	66.7 ± 7.2	66.9 ± 6.8	0.993	9
López-Cortés	2013	Ecuador	SA	PB	PCR-RFLP	3	9	92	0.072	104	1	4	105	0.027	110	NA	NA	0.001	9
Weiner	2012	Russia	Caucasian	PB	real-time PCR	15	134	221	0.222	370	16	96	173	0.225	285	69 ± 8.0	59 ± 17	0.580	7
Cai	2010	China	Asian	HB	PCR-RFLP	5	27	185	0.085	217	3	29	188	0.080	220	72.36 ± 12.16	72.83± 12.27	0.139	7
Marchal	2008	Spain	Caucasian	HB	Taqman	9	54	118	0.199	181	11	55	138	0.189	204	70.7 ± 7.29	70.3 ± 7.82	0.088	7
Kimura	2000	Germany	Caucasian	HB	PCR-RFLP	4	41	87	0.186	132	4	44	102	0.173	150	65.6 ± 6.0	62.0 ± 11.4	0.773	9

SA: South America; HWE: Hardy-Weinberg equilibrium of controls, HB: Hospital-based; PB: Population-based; MAF: Minor allele frequency; NOS: Newcastle-Ottawa Scale; RFLP: restriction fragment length polymorphism; NA: not available.