As mentioned above, the COMT Val158Met polymorphism is associated with a broad array of traits, including anxiety, pain sensitivity, and psychiatric disease susceptibility in humans. It is interesting to note that an unrelated polymorphism in the corresponding mouse gene (Comt1), causes differences in Comt1 gene expression and was associated with a number of behavioral differences in mice by three independent groups (Palmer and Dulawa. 2010; Kember et al. 2010; Li et al. 2010; Segall et al. 2010). This is an interesting example that shows how naturally occurring variants in mice permitted an additional cross-species comparison.
