COMT and schizophrenia: The association between COMT rs4680 A allele and better response to treatment with olanzapine (greater reduction in the PANSS0–6 total and a similar trend in PANSS0–6 positive subscale scores), detected in our study, agrees with findings showing that homozygous COMT rs4680 AA genotype carriers with schizophrenia had faster therapeutic response to olanzapine20, 21.