Table 1. Characteristics of the studies included in the meta-analysis.
| First author | Year | Country | Ethnicity | Genotyping method | Source of control | Number of case/control | NOS score | SNP |
|---|---|---|---|---|---|---|---|---|
| Yan | 2015 | China | Asian | PCR-RFLP | HB | 227/287 | 6 | 2 |
| Zhou | 2014 | China | Asian | PCR-RFLP | HB | 184/281 | 7 | 1,2 |
| Kou | 2014 | China | Asian | PCR-RFLP | HB | 208/532 | 6 | 2 |
| Cong | 2014 | China | Asian | PCR-RFLP | HB | 104/218 | 6 | 1 |
| Hao | 2013 | China | Asian | PCR-RFLP | HB | 169/282 | 7 | 2 |
| Zhang | 2013 | China | Asian | MassARRAY | PB | 771/998 | 7 | 1,2 |
| Shan | 2013 | China | Asian | PCR-RFLP | HB | 71/185 | 8 | 1 |
| Han | 2013 | China | Asian | FQ-PCR | HB | 1017/1009 | 7 | 2 |
| Xiang | 2012 | China | Asian | PCR-RFLP | HB | 73/100 | 6 | 1 |
| Kim | 2012 | Korea | Asian | PCR-RFLP | PB | 127/201 | 6 | 1,2 |
| Wang | 2011 | China | Asian | MassARRAY | HB | 199/384 | 8 | 1 |
| Akkız | 2011 | Turkey | Caucasian | PCR-RFLP | HB | 188/222 | 9 | 1 |
| Akkız | 2011 | Turkey | Caucasian | PCR-RFLP | HB | 153/185 | 9 | 2 |
| Qi | 2010 | China | Asian | PCR-LDR | HB | 361/391 | 8 | 2 |
PCR: polymerase chain reaction; RFLP: restriction fragment length polymorphism; FQ: fluorescent-probe real-time quantitative; LDR: ligation detection reaction; PB: population based; HB: hospital based; NOS: Newcastle-Ottawa Quality Assessment Scale; SNP: single-nucleotide polymorphism; SNP No.1: rs2910164, No 2: rs1161491.