COMT and schizophrenia: The minor (alternative) allele frequency for COMT rs4680 polymorphism (A allele) in patients with schizophrenia was 0.498 and 0.399 for COMT rs4818 polymorphism (C allele) which is consistent with estimated MAF in European populations (alternative allele frequency (A allele) = 0.508 for rs4680 and MAF (C allele) = 0.391 for rs4818) (ALFA project) (Supplementary Table S1).