MTHFR C677T Gene Polymorphism and Head and Neck Cancer Risk: A Meta-Analysis Based on 23 Publications

Table 1

Characteristics of case-control studies included in the meta-analysis.

							Genotype distribution
First author	Year	Country/region	Racial descent	Source of controls	Case	Control	Case			Control			Genotyping type	for HWE	MAF	Location
							CC	CT	TT	CC	CT	TT
Weinstein [12]	2002	Puerto Rico	Mixed	Population control	135	146	67	53	15	69	62	15	PCR-RFLP	0.85	0.32	Oral
Kureshi [20]	2004	Pakistan	Asian	NA	50	54	32	18	0	32	18	4	PCR-RFLP	0.52	0.24	HN
Neumann [21]	2005	USA	Caucasian	Hospital control	537	545	258	244	35	278	216	51	PCR-RFLP	0.34	0.29	HN
Capaccio [22]	2005	Italy	Caucasian	Population control	65	100	18	33	14	36	46	18	PCR-RFLP	0.62	0.41	HN
Vairaktaris [23]	2006	Greece	Caucasian	Population control	110	120	28	76	6	45	65	10	PCR-RFLP	0.04	0.35	Oral
Suzuki [24]	2007	Japan	Asian	Hospital control	237	711	88	113	36	252	331	128	TaqMan	0.29	0.41	HN
Reljic [25]	2007	Croatia	Caucasian	Population control	81	102	45	27	9	35	59	8	PCR-RFLP	0.01	0.37	HN
Hsiung [26]	2007	USA	Mixed	Population control	277	524	128	149		218	306		NA	NA	NA	HN
Hung [27]	2007	Europe	Caucasian	Hospital control	779	2530	373	327	79	1272	1025	233	TaqMan	0.20	0.30	HN
Solomon [28]	2008	India	Asian	NA	126	100	48	55	23	48	42	10	PCR-RFLP	0.86	0.31	Oral
Siraj [35]	2008	Saudi Arabia	Caucasian	Population control	49	511	30	18	1	372	126	13	PCR-RFLP	0.55	0.15	Thyroid
Ni [29]	2008	China	Asian	Hospital control	207	400	48	95	64	152	187	61	PCR-RFLP	0.78	0.39	Laryngeal
Rodrigues [36]	2010	Brazil	Mixed	Population control	100	100	44	43	13	46	40	14	PCR-RFLP	0.28	0.34	HN
Kruszyna [30]	2010	Poland	Caucasian	Population control	131	250	69	52	10	126	104	20	PCR-RFLP	0.82	0.29	Laryngeal
Cao [37]	2010	China	Asian	Population control	511	552	310	169	32	334	188	30	PCR-RFLP	0.60	0.23	NP
Tsai [31]	2011	Taiwan	Asian	Hospital control	620	620	391	186	43	322	236	62	PCR-RFLP	0.06	0.29	Oral
Supic [32]	2011	Serbia	Caucasian	Hospital control	96	162	50	32	14	80	66	16	PCR-RFLP	0.66	0.30	Oral
Sailasree [33]	2011	India	Asian	Hospital control	101	138	92	8	1	108	29	1	PCR-RFLP	0.53	0.11	Oral
Prasad [38]	2011	India	Asian	NA	97	241	86	10	1	228	12	1	PCR-RFLP	0.07	0.03	Thyroid
Fard-Esfahani [39]	2011	Iran	Asian	Hospital control	154	198	69	71	14	82	108	8	multiplex PCR	<0.01	0.31	Thyroid
Ozdemir [40]	2012	Turkey	Caucasian	NA	60	50	28	25	7	33	14	3	Real-time PCR	0.38	0.20	Thyroid
Galbiatti [34]	2012	Brazil	Mixed	Population control	322	531	130	147	45	226	250	55	PCR-RFLP	0.24	0.34	HN
Vylliotis [41]	2013	Greek/Germany	Caucasian	Population control	110	120	76	28	6	65	45	10	PCR-RFLP	0.58	0.27	Oral

HWE in controls.
MAF: minor allele frequency in controls.
NA: not applicable.
HN: head and neck.
NP: nasopharyngeal.