Table 1.
Characteristics of COMT gene Val158Met polymorphism genotype distributions in studies included in this meta-analysis.
| Genotypes GG/GA/AA | ||||||||
| First author | Year | Country | Ethnicity | Numbers of Case/Control | Case | Control | % of male (case/control) | Mean age (case/control) |
| Qian QJ | 2003 | China | Asian | 317/194 | 158/140/24 | 99/78/17 | 86.8/Na | 10.4/Na |
| Zhang XN | 2003 | China | Asian | 117/105 | 67/41/9 | 60/40/5 | 79.5/77.1 | 10.5/14.5 |
| Gao XP | 2006 | China | Asian | 54/30 | 25/25/4 | 13/16/1 | 83.3/73.3 | 9.9/9.5 |
| Chen JF | 2007 | China | Asian | 100/100 | 59/34/7 | 53/39/8 | 85/85 | 10.8/10.1 |
| Kereszturi E | 2008 | Hungary | Caucasian | 173/284 | 49/87/37 | 53/151/80 | 87.3/Na | 9.1/Na |
| Song EY | 2009 | Korea | Asian | 60/100 | 33/27/0 | 65/29/6 | 81.7/Na | 9.3/Na |
| Halleland H | 2009 | Norway | Caucasian | 435/383 | 84/214/137 | 71/188/124 | 53.3/41.4 | 34.4/27.8 |
| Zhang YB | 2009 | China | Asian | 114/76 | 58/43/10 | 40/25/11 | 80.7/68.4 | 12.5/13.1 |
| Xiong ZG | 2011 | China | Asian | 110/90 | 64/42/4 | 56/26/8 | Na/Na | Na/Na |
| Das M | 2011 | India | Asian | 126/96 | 138/114∗ | 109/83∗ | 90.9/76.9 | 7.3/19.5 |
| Chiho Y | 2013 | Japan | Asian | 50/32 | 20/30† | 4/28† | 100/100 | 9.7/16.9 |
| Carpentier PG | 2013 | Netherlands | Caucasian | 176/500 | 51/125‡ | 154/346‡ | 47.7/49.4 | 37.1/59.4 |
| Perkovic MN | 2013 | Coratia+ Estonia | Caucasian | 650/157 | 134/311/205 | 43/88/26 | 100/Na | 13.5/15 |
| Perkovic MN | 2014 | Coratia | Caucasian | 102/128 | 31/71‡ | 18/110‡ | 100/100 | 9.2/16.9 |
| Biehl SC | 2014 | German | Caucasian | 35/35 | 7/18/10 | 10/17/8 | 57.1/45.7 | 3636.6 |
| Jin J | 2016 | China | Asian | 594/154 | 326/228† | 86/68† | 85/74 | 10.1/9.3 |
| Pekcanlar Aka | 2018 | Turkey | Caucasian | 34/50 | 13/17/4 | 20/20/10 | 94/90 | 14.2/14.3 |