In human peripheral blood mononuclear cells (PBMCs) of schizophrenic subjects, selective alterations of DNA methylation at the promoter of the gene coding for the type-1 cannabinoid receptor (CNR1) were observed and confirmed in a well-validated animal model of schizophrenia, induced by prenatal methylazoxymethanol acetate (MAM). The gene discussed is CNR1; the disease is schizophrenia.