Table 1. Characteristics of the studies included in the meta-analysis.

First author (Year)	Country	Ethnicity	Type of cancer	Source of controls	Genotyping method	Total, N		GG genotype, N		GA genotype, N		AA genotype, N		HWE	Reference
						Cases	Controls	Cases	Controls	Cases	Controls	Cases	Controls
Kong (2000)	US	Mixed	HNPCC	FB	PCR-SSCP	49	37	9	10	36	21	4	6	0.51	[20]
McKay (2000)	UK	Caucasian	sCRC	PB	PCR-RFLP	100	101	25	34	58	50	17	17	0.849	[21]
Bala (2001)	Finland	Caucasian	HNPCC	FB	PCR-SSCP	146	186	50	47	70	97	26	42	0.551	[22]
Kong (2001)	US	Caucasian	sCRC	PB	PCR-SSCP	156	152	36	45	71	84	49	23	0.112	[20]
Porter (2002)	UK	Caucasian	Mixed	PB	PCR-RFLP	334	171	85	60	175	81	74	30	0.768	[24]
Porter (2002)	UK	Caucasian	HNPCC	PB	PCR-RFLP	99	171	30	60	47	81	22	30	0.768	[24]
Porter (2002)	UK	Caucasian	sCRC	PB	PCR-RFLP	128	171	34	60	65	81	29	30	0.768	[24]
Grieu (2003)	Australia	Caucasian	sCRC	HB	PCR-SSCP	569	327	142	90	313	158	114	79	0.556	[25]
Le Marchand (2003)	US	Mixed	Mixed	PB	PCR-RFLP	504	624	109	164	253	315	142	145	0.792	[26]
Le Marchand (2003)	US	Caucasian	sCRC	PB	PCR-RFLP	138	161	29	50	75	85	34	26	0.311	[26]
Le Marchand (2003)	US	Asian	sCRC	PB	PCR-RFLP	296	380	75	96	143	195	78	89	0.603	[26]
Lewis (2003)	US	Caucasian	sCRC	HB	PCR-RFLP	161	213	51	84	84	98	26	31	0.781	[27]
Hong (2005)	Singapore	Asian	sCRC	PB	PCR-RFLP	254	101	55	12	128	50	71	39	0.505	[28]
Huang (2006)	Taiwan	Asian	sCRC	HB	PCR-RFLP	831	1052	126	199	411	464	294	389	0.004	[29]
Jiang (2006)	India	Asian	Mixed	HB	PCR-RFLP	301	291	46	56	130	145	125	90	0.86	[30]
Kruger (2006)	Germany	Caucasian	HNPCC	PB	Multiplex PCR	315	245	110	73	144	121	61	51	0.947	[31]
Probst-Hensch (2006)	Singapore	Asian	Mixed	PB	TaqMan PCR	300	1169	56	207	132	548	112	414	0.272	[32]
Schernhammer (2006)	US	Caucasian	Mixed	PB	TaqMan PCR	610	1237	125	264	311	593	174	380	0.25	[33]
Forones (2008)	Brazil	Mixed	Mixed	HB	PCR-RFLP	123	120	36	34	66	67	21	19	0.141	[34]
Grunhage (2008)	Germany	Caucasian	Mixed	HB	PCR-RFLP	194	218	37	48	93	109	64	61	0.958	[35]
Grunhage (2008)	Germany	Caucasian	HNPCC	HB	PCR-RFLP	98	218	13	48	50	109	35	61	0.958	[35]
Grunhage (2008)	Germany	Caucasian	sCRC	HB	PCR-RFLP	96	218	24	48	43	109	29	61	0.958	[35]
Talseth (2008)	Australia/Poland	Caucasian	HNPCC	HB	TaqMan PCR	157	153	34	42	78	80	45	31	0.527	[36]
Tan (2008)	Germany	Mixed	Mixed	PB	PCR-RFLP	498	600	120	147	263	310	115	143	0.414	[37]
Jelonek (2010)	Poland	Caucasian	sCC	PB	PCR-RFLP	50	153	12	44	33	71	5	38	0.383	[38]
Kanaan (2010)	US	NS	sCRC	HB	PCR-HLC	75	93	19	24	39	48	17	21	0.748	[39]
Liu (2010)	China	Asian	Mixed	PB	PCR-RFLP	373	838	66	160	187	429	120	249	0.303	[40]
Yaylim-Eraltan (2010)	Turkey	Caucasian	Mixed	HB	PCR-RFLP	57	117	9	29	28	60	20	28	0.781	[41]

HWE: Hardy–Weinberg equilibrium; US: United States; UK: United Kingdom; HNPCC: hereditary nonpolyposis colorectal cancer; sCRC: sporadic colorectal cancer; sCC: sporadic colonic cancer; FB: family-based study; PB: population-based study; HB: hospital-based study; PCR: polymerase chain reaction; SSCP: single-stranded conformation polymorphism; RFLP: restriction fragment length polymorphism; HPLC: high-performance liquid chromatography.