Table 1 summarizes genotypic distributions of the polymorphisms in the three genes and the scores for NEO PI-R and STAI according to the genotypes. The distributions of all six polymorphisms follow the Hardy-Weinberg equilibrium. In the analysis based on each polymorphism, one-way ANCOVA showed significant difference in the score for State Anxiety according to the genotype of the -141C Ins/Del polymorphism in the DRD2 gene (F = 3.53, df = 2, p = 0.031); That for Trait Anxiety, according to the genotype of the Ser311Cys polymorphism in the DRD2 gene or the PstI site polymorphism in the TH gene (F = 3.96, df = 2, p = 0.048 and F = 3.25, df = 2, p = 0.041, respectively). However, statistical levels of these differences became insignificant after Bonferroni correction. No other significant difference in the scores for the NEO PI-R or STAI factors was observed in this comparison.
In epistatic analysis, no significant deviation of independence was observed for all combinations of polymorphisms in the different genes (data not shown). Two-way ANCOVA showed significant interactions on the scores for Neuroticism and Trait Anxiety between the DRD2 -141C Ins/Del and TH Val81Met polymorphisms (F = 3.18, df = 4, p = 0.015 and F = 3.43, df = 4, p = 0.010, respectively). However, statistical level of this interaction became insignificant after Bonferroni correction. No other significant interaction of the polymorphisms was observed on the NEO PI-R or STAI factors.