The catechol-O-methyltransferase (COMT) gene has received extensive attention due to its effects on dopamine metabolism and links to disorders such as schizophrenia. A polymorphism within COMT results in a valine (Val) to methionine (Met) substitution with a lower enzymatic activity and resulting higher dopamine levels in prefrontal cortical regions where the gene is densely expressed (Tunbridge et al. 2007). A comparison of cortical thickness in 209 healthy children and adolescents from the CPB study with the Val/Val, Val/Met, and Met/Met alleles found a stepwise increase in cortical thickness in the right inferior frontal and right superior/middle temporal gyrus with each additional Met allele (Shaw et al. 2009).
