Another study analyzed the DRD3, DRD2, and DARPP-32 (dopamine and cyclic adenosine 3′,5′-monophosphate-regulated phosphoprotein-32) mRNA levels in peripheral blood lymphocytes from healthy subjects, patients with an unspecified psychotic disorder, and patients with schizophrenia/schizophreniform disorder, examining the relationship between these genes and the psychopathological state of the patients. Here, DRD3 is linked to psychotic disorder.