KALRN is a protein-coding gene that has been associated with stroke (Krug et al., 2010), coronary heart disease (Wang et al., 2007; Beręsewicz et al., 2008; Krug et al., 2010), schizophrenia (Hill et al., 2006; Hayashi-Takagi et al., 2010; Bradshaw and Porteous, 2012), and adult attention-deficit/hyperactivity disorder (Lesch et al., 2008). This evidence concerns the gene KALRN and attention deficit-hyperactivity disorder.