Does measurement instrument moderate the association between the serotonin transporter gene and anxiety-related personality traits? A meta-analysis.

We attempted to replicate the findings of two recent meta-analyses that personality inventory moderates the association between the serotonin transporter gene and anxiety-related traits. A total of 24 studies contributed to the meta-analysis, of which three reported genotype frequencies that deviated from Hardy-Weinberg (HW) equilibrium. We found some support for the view that results depend on the type of questionnaire used, although in a direction opposite to that previously reported. Contrasts between the S/S and L/L groups were significant for TCI/TPQ harm avoidance studies (P=0.0024) but not NEO neuroticism (P=0.9757). When studies not in HW equilibrium were excluded the TCI/TPQ result for the S/S genotype still exceeded our 5% threshold, although with reduced significance (P=0.0082), and the NEO result remained nonsignificant (P=0.9109). While we cannot rule out an association between the 5HTT gene and anxiety-related traits, particularly for TCI/TPQ harm avoidance, our findings do indicate that the effect, if present, is small. Our results emphasise the importance of complete ascertainment of studies and the identification of relevant sources of heterogeneity.