Table 1. Characteristics of studies included in the meta-analysis.
| References | Country (ethnicity) | Smoking status | Genotyping method | Source of control | Case/ Control |
HWE | ||
|---|---|---|---|---|---|---|---|---|
| Sample | G | A | ||||||
| Endo 2001 | Japan (Asian) | Unknown | PCR-SSOP | PB | 46/104 | 90/204 | 2/4 | Yes |
| Shapira 2001 | Israel (Caucasian) | Unknown | PCR-TaqMan | PB | 16/27 | 29/47 | 3/7 | Yes |
| Pérez 2004 | Chile (Chileans) | Non-smokers | PCR-RFLP | PB | 27/30 | 49/55 | 5/5 | Yes |
| Brett 2005 | UK (Caucasian) | Mixed | PCR-SSP | PB | 50/97 | 76/155 | 24/39 | No |
| Sakellari 2006 | Greek (Caucasian) | Mixed | PCR | PB | 46/90 | 78/156 | 14/24 | Yes |
| Zhu 2007 | China (Asian) | Mixed | PCR-RFLP | HB | 64/78 | 111/144 | 17/12 | Yes |
| de Freitas 2007 | Brazil (Caucasian) | Non-smokers | PCR-RFLP | PB | 30/70 | 46/102 | 14/38 | Yes |
| Guzeldemir 2008 | Turkey (Caucasian) | Non-smokers | PCR | PB | 31/31 | 46/55 | 16/7 | Yes |
| Schulz 2008 | Germany (Caucasian) | Mixed | PCR | PB | 69/52 | 109/86 | 29/18 | Yes |
| Menezes 2008 | Brazil (Brazilian) | Mixed | PCR-RFLP | HB | 38/51 | 61/73 | 15/29 | Yes |
| Moreira 2009 | Brazil (Brazilian) | Mixed | PCR-RFLP | HB | 55/43 | 95/72 | 15/14 | Yes |
| Erciyas 2010 | Turkey (Caucasian) | Non-smokers | PCR-SSP | PB | 35/85 | 55/154 | 15/16 | Yes |
| Scapoli 2011 | Italy (Caucasian) | Unknown | PCR-MassARRAY | PB | 122/246 | 1.19(0.81–1.74)* | Yes | |
| Ebadian 2013 | Iranian (Caucasian) | Non-smokers | PCR-RFLP | PB | 58/60 | 74/88 | 42/32 | Yes |
| Yang 2013 | China (Asian) | Mixed | PCR-RFLP | HB | 180/180 | 275/292 | 85/68 | Yes |
| Özer Yücel 2015 | Turkey (Caucasian) | Non-smokers | PCR-RFLP | HB | 38/26 | 56/35 | 20/17 | No |
PB, population-based; HB, hospital-based; HWE, Hardy-Weinberg equilibrium; Mixed, smokers and non-smokers; *odds ratio with its 95% confidence interval.