ADCY1 and depressive symptom measurement: While the s-antigen visual arrestin is primarily involved in ophthalmological disorders, it has been shown to also be expressed in nonphotosensitive cells controlled by the beta adrenergic G-protein–mediated adenylate cyclase system (Faure and Mirshahi, 1990) and might be linked to T-cell activation and cytokine response in healthy probands and thus potentially also to immune-mediated processes relevant to depression (see Morgan et al., 2002).