Association study between a functional polymorphism of tyrosine hydroxylase gene promoter and personality traits in healthy subjects.

According to the Cloninger's theory, personality consists of temperaments, which are automatic emotional reactions and habits, and characters, which are the self-concepts about goals and values. It has been suggested that temperaments are highly heritable and related to catecholaminergic neurotransmission. Tyrosine hydroxylase (TH) is the initial and rate-limiting enzyme in the biosynthesis of catecholamines such as dopamine and norepinephrine, which are deeply involved in human mental functions and behaviors. It has recently been reported that the C-824T single nucleotide polymorphism in the promoter region of the TH gene (rs10770141) affects promoter activity of the TH gene and urinary catecholamine levels. In the present study, the association of this polymorphism with personality traits was examined in 740 healthy Japanese subjects. Personality traits were assessed by the Temperament and Character Inventory (TCI), and the TH genotype was detected by a PCR-RFLP method. In total subjects, there were no significant differences in the seven TCI dimension scores between the TH genotype groups. In males, the subjects with the T allele predictive of elevated levels of dopamine and norepinephrine had lower scores of novelty seeking than those without this allele, while in females none of the TCI scores was different between the two genotype groups. The present study thus suggests that the C-824T polymorphism in the TH gene promoter may affect the personality trait of novelty seeking in healthy males. However, taken the effects of multiple comparisons into account, the present result should be interpreted with caution, necessitating a replication in a different sample.