Table 1. General characteristics of studies included in the meta-analysis.
| Author | Year | Country | Ethnicity | Source of controls | Matching criteria | Case | Control | SNP studied | HWEa |
| Joseph | 2005 | India | Asian | Hospital-based | sex, age, ethnicity | 117 | 117 | 194, 280, 399 | Yes |
| Pakakasama | 2007 | Thailand | Asian | Hospital-based | ethnicity | 108 | 317 | 194, 280, 399 | Yes |
| Batar | 2009 | Turkey | Caucasian | Hospital-based | sex, age, ethnicity | 70 | 75 | 194, 399 | Yes |
| Meza-Espinoza | 2009 | Mexico | Mestizo | Hospital-based | ethnicity | 120 | 120 | 194, 280, 399 | Yes |
| Tumer | 2010 | Turkey | Caucasian | Hospital-based | ethnicity | 167 | 190 | 194, 399 | Yesb |
| Canalle | 2011 | Brizal | Mixed | Hospital-based | - | 201 | 361 | 194,399 | Yes |
| Stanczyk | 2011 | Poland | Caucasian | Hospital-based | ethnicity | 97 | 131 | 399 | Yes |
a
HWE Hardy–Weinberg equilibrium.
b
Genotype distributions of Arg194Trp in the controls were significantly deviated from HWE 399 Arg399Gln, 194 Arg194Trp, 280 Arg280His.