Finally, two more candidate genes were identified: (1) ALDH4A1, which has been linked to a rare autosomal recessive human disorder, Hyperprolinemia type II, with the phenotypes of irritability and aggressive behavior [100]; and (2) ADORA2A, which has been previously associated with panic disorder and anxious personality in humans [101]. Here, ALDH4A1 is linked to hyperprolinemia type 2.