While all the dopamine receptors are important for brain homeostasis, D2 dopamine receptor (Drd2) is closely related with brain disorders including schizophrenia (Wong et al. 1986), Parkinson’s disease (Chaudhuri and Schapira 2009) and drug addiction (Volkow et al. 2007). The gene discussed is DRD2; the disease is schizophrenia.