Table 1.

The Main Characteristics of the Eligible Literatures Included in the Meta-Analysis.

						No. of case				No. of control
First author	Year	Control source	Country	Ethnicity	Tumor site	N	AA	AG	GG	N	AA	AG	GG	HWE
Ammar	2020	Hospital	Jordan	Asian	Head & neck	99	67	30	2	89	43	43	3	0.047
Applebaum	2009	Healthy	USA	Mixed	Head & neck	483	192	229	62	547	232	246	69	0.762
Bogela	2011	Hospital	China	Asian	Larynx	58	32	22	4	116	61	48	7	0.542
Csejtei	2009	Healthy	Hungary	Caucasians	Head & neck	108	50	47	11	102	53	41	8	0.985
Demokan	2005	Healthy	Turkey	Caucasians	Oral	95	42	41	12	98	39	46	13	0.922
Dos	2013	Healthy	Brazil	Brazilian	Oral	150	64	62	24	150	62	54	34	0.002
Gajecka	2005	Healthy	Poland	Caucasians	Larynx	293	106	153	34	319	124	145	50	0.484
Gugatschka	2011	Healthy	Austria	Caucasians	Head & neck	168	70	74	24	463	204	198	61	0.24
Hakan	2017	Hospital	Turkey	Mixed	Oral	111	44	22	45	148	133	15	0	0.516
Harth	2008	Healthy	Germany	Caucasians	Head & neck	310	114	166	30	300	143	121	36	0.189
He	2010	Hospital	China	Asian	Larynx	72	22	38	12	72	43	22	7	0.116
Jelonek	2010	Healthy	Poland	Caucasians	Head & neck	104	47	50	7	110	35	62	13	0.068
Kietthubthew	2006	Hospital	Thailand	Asian	Oral	106	55	45	6	164	67	74	23	0.724
Kostrzewska-Poczekai	2013	Healthy	Poland	Caucasians	Head & neck	290	110	154	26	158	50	81	27	0.55
Kowalski	2009	Hospital	Poland	Caucasians	Head & neck	92	37	44	11	124	49	53	13	0.253
Krupa	2011	Hospital	Poland	Caucasians	Larynx	253	93	111	49	253	105	113	35	0.238
Kumar	2012	Healthy	India	Asian	Head & neck	278	128	124	26	278	98	144	36	0.132
Li	2007	Hospital	USA	Caucasians	Head & neck	830	335	374	121	854	360	285	109	0.577
Majumder	2005	Hospital	India	Asian	Oral	310	135	143	32	348	158	163	27	0.088
Majumder	2007	Healthy	India	Asian	Oral	309	134	143	32	385	170	179	36	0.255
Matullo	2006	Healthy	Italy	Caucasians	Head & neck	82	34	38	10	1094	484	482	128	0.632
Olshan	2002	Hospital	USA	Caucasians	Head & neck	98	45	50	3	161	62	82	17	0.183
Pelin	2015	Hospital	Turkey	Caucasians	Head & neck	55	21	27	7	69	22	35	12	0.763
Ramachandran	2006	Healthy	India	Asian	Oral	110	46	48	16	110	73	33	4	0.91
Rim	2014	Hospital	Tunisia	Caucasians	Head & neck	169	12	78	79	261	14	165	82	0.001
Rydzanicz	2005	Healthy	Poland	Caucasians	Head & neck	182	63	98	21	143	59	63	21	0.535
Sturgis	1999	Hospital	USA	Mixed	Head & neck	203	94	77	32	424	181	197	46	0.483
Tae	2004	Hospital	Korea	Asian	Head & neck	129	69	51	9	157	86	64	7	0.25
Varzim	2003	Healthy	Portugal	Caucasians	Larynx	88	37	40	11	178	80	80	18	0.759
Yuan	2012	Healthy	China	Asian	Head & neck	390	221	146	23	886	481	339	66	0.558