Catch me if you can: Are catechol- and indoleamine genes pleiotropic QTLs for common mental disorders?

A number of recent independent studies have reported association between genes of the catechol- and indoleamine systems and various complex human behavioural traits or disorders. While these findings must be treated with caution until replicated, they may represent some of the first successes of the candidate-gene allelic-association strategy in psychiatry. It is tempting to speculate that these gene families contain quantitative trait loci with pleiotropic effects, which will provide the key to the understanding of the interaction between genes and environment in behavioural disorders.