CDH13 and attention deficit-hyperactivity disorder: The protein encoded by the CDH13 gene is one of numerous cadherins expressed in the brain, which have been shown to regulate many neural processes (Redies et al. 2012) and CDH13 has been implicated in ADHD through genome-wide association and extended pedigree linkage studies (Lesch et al. 2008; Rivero et al. 2012).