In summary, an inverse connection between CYP1A1 and miR-21; CYP1B1 with miR-27b and miR-200c; and CYP1A2 with miR-122 points to a miRNA-CYP enzyme regulatory network in schizophrenia that can be readily detected in the blood. This evidence concerns the gene CYP1A2 and schizophrenia.