Mean DST-Cortisol levels. The means of the DST-Cortisol levels in each genotype of rs1143633 (Figure 2a) and rs16944 (Figure 2b) are shown. Error bars indicate the standard errors of the means. Asterisks in the graph indicate significance levels of the Tukey's post hoc test. * P < 0.01, ** P < 0.001, *** P < 0.0001.