Inoue-Murayama / Poster

Evolution of personality-related genes in primates

M. Inoue-Murayama¹, Y. Niimi¹, O. Takenaka², and Y. Murayama³
¹Faculty of Agriculture, Gifu University, Gifu 501-1193, JAPAN
²Primate Research Institute, Kyoto University, Inuyama 484-8506, JAPAN
³National Institute of Animal Health, Tsukuba 305-0856, JAPAN

The dopamine receptor D4 (DRD4) and the serotonin transporter (5-HTT) genes have attracted special interest as genes related to personality traits. To examine the diversities of these genes in the evolutionary context, we sequenced their polymorphic regions in non human primates. Human DRD4 is polymorphic in terms of the repeat numbers of the 48-bp sequence located in the third cytoplasmic loop of the receptor and it has been indicated that individuals with long repeats (6 or more) in the DRD4 gene were found to display higher scores in a personality test for novelty seeking than did those with shorter repeats. Four or more repeated sequences have been reported in the DRD4 genes of simians, whereas we found most prosimians to have one or two unit(s) of the 48-bp sequence, indicating that the ancestral primate may have had one 48-bp unit, that duplication of the unit occurred at the stage of prosimians, and that the repeat number of units increased after divergence into simian primates. Tandem repeats consisting of 20-23 bp-length units are located in the promoter region of human 5-HTT gene and it has been shown that individuals with 14 repeats in the promoter displayed higher scores in a personality test for anxiety/neuroticism than did those with 16 repeats. We found that all chimpanzees examined shared only the 17.5 repeat allele, while polymorphism was observed in the other apes and the 16 and 20 repeat alleles were most frequent in gorillas and orangutans, respectively. 5-HTT gene was highly polymorphic in gibbons and the 17 and 23 repeat alleles were dominant among 5 alleles. These findings suggested that the frequency of alleles with short repeated sequences tended to increase during the process of hominization.

Inoue-Murayama M, Takenaka O, Murayama, Y. 1998. Origin and divergence of tandem repeats of primate D4 dopamine receptor genes. Primates 39:217-224.