Figure 2. Association between tyrosine hydroxylase intron 4 genotypes and activity-impulsivity related phenotypes.

(A) Dog-ADHD RS activity-impulsivity scale; (B) Activity-Impulsivity Behavioural Scale (AIBS). 1/2 genotype represents the group of individuals possessing at least one short allele. Subjects in the 2/2 genotype possess two long alleles. Box-plot figures with sample minimum and maximum, lower and upper quartiles and medians. * indicates significant differences (* p<0.05; ** p<0.01).