Table 1. Characteristics of included studies.

ID	Authors	Year	Country	SNPs		OR (95% CI)	Study design	Statistical analysis (HWE, p -Value )
1	Tarek et al 10	2013	Egypt	1059 (rs1800947)	GC + CC	3.59 (1.30–9.93)	Case–control	p  = 0.001
					C allele	3.37 (1.29–8.82)		p  = 0.01
2	Hsu et al 12	2010	Taiwan	rs3091244		1.62 (1.05–2.49)	Cross-sectional	p  = 0.029
3	Nikpour et al 13	2015	Iran	T allele	rs3091244	1.70 (0.98–2.96)	Case–control	p  = 0.059
ID	Study	Year	Country	SNPs		Population ( N event/case) / ( N event/control)	Study design	Statistical analysis (HWE, p -Value )
4	Darya et al 11	2011	UK	rs1205		(618/2100)/(141/1875)	Cohort	p  = 0.59
				rs3093068		(616/2093)/(141/1875)		p  = 0.88

Abbreviations: CI, confidence interval; HWE, Hardy–Weinberg equilibrium; OR, odds ratio; SNP, single-nucleotide polymorphism.