Background: We conducted a meta-analysis to re-evaluate the role of the dopamine D4 receptor gene 48-base-pair- repeat (DRD4) polymorphism in mood disorders.
Methods: DRD4 allele frequencies were compared between 917 patients with unipolar (UP) or bipolar affective disorder (BP) and 1164 control subjects from 12 samples, using the Cochrane Review Manager.
Results: An association was found between all mood disorder groups and DRD4.2. After correcting for multiple testing, the association between DRD4.2 and BP dropped to insignificance; however, the evidence of an association between the DRD4.2 allele and UP (p < .001) and the combined group (p < .001) remained. There was no evidence for heterogeneity or publication bias.
Conclusions: These findings suggest that the DRD4.2 allele is a risk allele for depression symptomatology. Meta-analysis may be a valuable objective tool for a quantitative summary of evidence for association studies in psychiatric genetics.