However, D2R agonists may elicit severe adverse effects such as valvular heart disease or psychiatric disturbances (Lees, 2005; Hisahara and Shimohama, 2011; Pedrosa and Timmermann, 2013), which are probably induced by activating D3Rs and D4Rs (Rich et al., 1995; McCall et al., 2005). The gene discussed is DRD2; the disease is heart valve disorder.