When an arbitrary threshold for the combined RGS1 and CCL4 expression level analysis was set to be below 50% of the mean level of RGS1 and CCL4 expressed in healthy controls, the combination of both genes resulted in a specificity of detection of 97% in identifying the PBMC samples of schizophrenia patients correctly (Fig. 3b). The gene discussed is CCL4; the disease is schizophrenia.