2000; Ghate et al. 2007; Van Waes et al. 2011) and whose expression, restricted to the projecting medium spiny neurons, is regulated by dopaminergic and glutamatergic afferents (Massart et al. 2009), two systems that have been implicated in the pathogenesis of SZ (Grace 1991; Carlsson et al. 2001) and BD (Cousins et al. 2009; Machado-Vieira et al. 2012). Moreover, transcriptomic studies have shown that Gpr88 expression is regulated by lithium (Brandish et al. 2005), antidepressant (Conti et al. 2006) and psychostimulant treatments (Ogden et al. 2004). Here, GPR88 is linked to Behcet disease.