We quantified mGlu2R and mGlu3R protein immunodensities, mRNA levels, and the load of histone posttranslational modifications (HPTMs) at the GRM2 and GRM3 genes in a relatively large case-control postmortem brain cohort of well-characterized schizophrenia cases with qualitative and quantitative assessment of antipsychotic drugs in blood and brain tissue samples, respectively. The gene discussed is GRM2; the disease is schizophrenia.