Table 1.
Overview of findings listed on www.szgene.org and results of recent meta-analyses on 11 core dopamine-related genes.
| SZgene.org Summary | |||
|---|---|---|---|
| Gene | Total # case-control studies1 (% positive2) | Total # family-based studies1 (% positive2) | Summary of prior published meta-analytic results3 |
| COMT | 63 (23.8) | 15 (26.7) | Conflicting results from meta-analyses: three suggested that variants in COMT are unlikely to contribute to schizophrenia risk (Munafo et al., 2005; Okochi et al., 2009; Shi et al., 2008), while another reported some support for multiple variants (Allen et al., 2008). A fourth reported a protective effect of heterozygosity at rs4680 (Costas et al., 2011). |
| DBH | 11 (9.1) | 3 (0) | No support for an association between a common insertion/deletion in DBH and schizophrenia (Dai et al., 2014). |
| DDC | 5 (0) | 1 (0) | No meta-analytic results available. No evidence for association between DDC and paranoid schizophrenia (Zhang et al., 2004). |
| DRD1 | 10 (10.0) | 2 (0) | Meta-analytic results provided support for an association between one DRD1 variant and schizophrenia (rs5326) but not another (rs4532) (Pan et al., 2014). A separate meta-analysis reported weak support for rs4532 (Allen et al., 2008). |
| DRD2 | 46 (34.8) | 8 (25.0) | One prior meta-analysis reported an association at this locus (Allen et al., 2008), but another found no support for an association (Shi et al., 2008). |
| DRD3 | 66 (36.4) | 8 (12.5) | Multiple meta-analysis have reported no evidence of association (Jonsson et al., 2004; Nunokawa et al., 2010; Utsunomiya et al., 2008), though earlier meta-analyses did report an association (Dubertret et al., 1998; Williams et al., 1998). |
| DRD4 | 23 (8.7) | 5 (0) | Two meta-analyses reported modest support for association between variants in DRD4 and schizophrenia (Allen et al., 2008; Shi et al., 2008), but another earlier meta-analysis found no evidence of association (Glatt et al., 2003). The meta-analysis by Jonsson et al. (2003) reported mixed evidence across variants. |
| DRD5 | 7 (42.9) | 2 (0) | No meta-analytic results are available. |
| MAOA | 19 (5.3) | 0 (0) | A meta-analysis found no overall support for an association between two common polymorphisms and schizophrenia (Li and He, 2008). |
| SLC6A3 | 16 (25.0) | 5 (60.0) | The only meta-analysis available found no association between a common VNTR and schizophrenia (Gamma et al., 2005). |
| TH | 10 (40.0) | 1 (0) | Only one meta-analysis was found, and it reported no association between TH and schizophrenia (Li and He, 2006). |
1
Because the current analyses are based on summary statistics from samples of predominantly European descent, we report here only the studies of Caucasian subjects in SZgene.org. Some studies included overlapping samples; this non-independence has not been accounted for in here.
2
“Positive” in this context means at least one marker tested had p<0.05.
3
A more comprehensive review of four of these genes, not limited to meta-analyses, is available from Talkowski et al. (2007).