Human personality dimensions of persistence and harm avoidance associated with DRD4 and 5-HTTLPR polymorphisms.

The associations of human personality traits as measured by the Temperament and Character Inventory (TCI) with two genetic polymorphisms, the dopamine D4 receptor (DRD4) gene exon III repeat polymorphism (VNTR) and the serotonin transporter-linked functional polymorphism (5-HTTLPR) are presented in a population of 157 ethnically homogeneous Caucasians. No association was found between Novelty Seeking and the DRD4 VNTR, but male individuals with a 7-repeat allele exhibited significantly lower Persistence scores. The 5-HTTLPR polymorphism itself had no significant effect on any of the temperament dimensions, but a significant DRD4 VNTR x 5-HTTLPR interaction was observed for Harm Avoidance, the subgroup with a s/s 5-HTTLPR, 7-repeat DRD4 genotype showed a higher mean Harm Avoidance score than the other groups. These results are discussed in relation to the recent findings on infant temperament. Association between the DRD4 7-repeat allele and Persistence can be theoretically linked to the 7-repeat allele as a risk factor for attention deficit hyperactivity disorder.