No association of 5-HT2C, 5-HT6, and tryptophan hydroxylase-1 gene polymorphisms with personality traits in the Japanese population

Serotonin 2C receptor (5-HT 2C ), serotonin 6 receptor (5-HT 6 ), and tryptophan hydroxylase-1 (TPH1) genes could be candidates for personality-related genes considering the role of serotonin in various mental functions and behavior. However, a limited number of studies have investigated the association between these genes and personality traits. In the present study, we investigated the three serotonin-related genes, 5 - HT 2C , 5 - HT 6 , and TPH1 genes, in relation to personality traits in the Japanese population. The Cys23Ser polymorphisms in the 5 - HT 2C gene, the 267T/C polymorphism of the 5 - HT 6 gene, and the 779A/C polymorphisms in the TPH1 gene were genotyped in 253 healthy Japanese subjects. Personality traits were evaluated by using the Revised NEO Personality Inventory (NEO PI-R) and the State-Trait Anxiety Inventory (STAI). As a result, no significant association was observed between the polymorphisms and the NEO PI-R or the STAI scores. The present results did not provide evidence for the association between the three serotonin-related genes and personality traits. The genes might not have major role in the development of personality traits, although further investigation with larger sample size may be recommended for conclusion.