PDE4D and schizophrenia: Polymorphisms in human PDE4B are associated with schizophrenia; we have previously reported complete disruption of the PDE4B gene in two independent subjects with psychosis, and that PDE4B and PDE4D interact dynamically with the schizophrenia candidate gene DISC1 to regulate cAMP (Clapcote et al., 2007, Millar et al., 2005, Millar et al., 2007).