Table 1.

Characteristics of studies included in the systematic review and meta-analysis

	Study	Year	Country	Ethnicity	Genotyping method	Cases	Controls	Genotype frequency in cases			Genotype frequency in controls			PHWE
-592C/A								CC	CA	AA	CC	CA	AA
	Shih, C. M.	2005	Taiwan	Asian	PCR-RFLP	154	205	18	70	66	13	76	116	0.9
	Colakogullari, M.	2008	Turkey	Asian	PCR-SSP	44	59	19	23	2	27	25	7	0.74
	Vogel, U.	2008	Denmark	European	PCR	403	744	241	149	13	452	250	42	0.34
	Liang, H. G.	2011	China	Asian	PCR-RFLP	116	120	11	36	69	7	44	69	0.99
	Hsia, T. C.	2014	Taiwan	Asian	PCR-RFLP	358	716	40	145	173	71	277	368	0.08
	Zhang, Y. M.	2015	China	Asian	PCR-RFLP	330	336	110	156	64	75	176	85	0.37
-819C/T								CC	TC	TT	CC	TC	TT
	Seifart, C.	2005	German	European	PCR-RFLP	77	242	42	31	4	140	88	14	0.97
	Shih, C. M.	2005	Taiwan	Asian	PCR-RFLP	154	205	30	58	66	15	86	104	0.63
	Colakogullari, M.	2008	Turkey	Asian	PCR-SSP	44	59	19	23	2	26	26	7	0.9
	Zhang, Y. M.	2015	China	Asian	PCR-RFLP	330	336	87	135	108	47	144	145	0.25
-1082G/A								AA	AG	GG	AA	AG	GG
	Seifart, C.	2005	German	European	PCR-RFLP	115	243	30	54	31	86	115	42	0.74
	Colakogullari, M.	2008	Turkey	Asian	PCR-SSP	44	59	11	30	3	33	21	5	0.53
	Hart, K.	2011	Norway	European	TaqMan	436	435	120	207	109	104	226	105	0.41
	Hsia, T. C.	2014	Taiwan	Asian	PCR-RFLP	358	716	273	69	16	561	130	25	0.07

P_HWE, p value for Hardy-Weinberg Equilibrium test in controls.