SEROTONIN TRANSPORTER PROTEIN GENE POLYMORPHISM AND PERSONALITY MEASURES IN AFRICAN-AMERICAN AND EUROPEAN-AMERICAN SUBJECTS

Objective: The SLC6A4 locus encodes the serotonin transporter, which i n turn mediates the synaptic inactivation of the neurotransmitter sero tonin. A polymorphism located in the 5' promoter region of the gene is associated with altered transcriptional activity of SLC6A4; an earlie r study reported an association of the polymorphism with anxiety- and depression-related traits, including harm avoidance and neuroticism. T he authors attempted to replicate this finding. Method: They assessed genotype at the SLC6A4 promoter polymorphism, and an additional polymo rphism in intron 2, in 322 American subjects of European and African a ncestry, some with diagnoses of a personality disorder or substance de pendence and some normal comparison subjects. Harm avoidance was measu red by the Tridimensional Personality Questionnaire in all subjects, a nd neuroticism was measured by the NEO Five-Factor Inventory in 185 su bjects. Allele frequencies in the groups were com pared, and hierarchi cal multiple regression was used to examine the correlation of demogra phic features, psychiatric diagnostic group, and genotype with harm av oidance and neuroticism scores. Results: Although the demographic fact ors and psychiatric diagnoses had effects on harm avoidance and neurot icism scores, there was no main effect of genotype on these personalit y measures. In the context of these overall negative findings, interac tions were observed between sex and promoter system genotype and betwe en race and promoter system genotype which suggest that the present fi ndings are not wholly inconsistent with those of the earlier study. Co nclusions: The authors were unable to replicate the association findin g. The specific phenotypic composition of the groups studied with resp ect to other behaviors could have influenced ability to detect associa tion of SLC6A4 polymorphisms with personality measures; population str atification for this locus is also of potential importance.