title: Dopamine D2 receptor gene polymorphisms predict well the response to dopamine antagonists at therapeutic dosages in patients with schizophrenia.
abstract: Previous reports have shown that both A1 allele carriers of TaqI A and Del allele non-carriers of -141C Ins/Del for dopamine D(2) receptor (DRD(2)) gene polymorphisms have a better antipsychotic drug response. The present study aimed to examine the validity of a combination of these two DRD(2) polymorphisms as predictors for response to DRD(2) antagonists. The subjects consisted of 49 acutely exacerbated inpatients with schizophrenia treated with bromperidol (30 cases, 6-18 mg/day) or nemonapride (19 cases, 18 mg/day) for 3 weeks. Brief Psychiatric Rating Scale and Udvalg for Kliniske Undersøgelser side-effects rating scale were used for clinical assessments. DRD(2) genotypes were determined using a polymerase chain reaction method. In the overall 49 subjects, combined DRD(2) polymorphisms weakly predicted the response to DRD(2) antagonists (Fisher exact test, P = 0.049), that is, good response in A1(+) or Del(-) subjects and poor response in A1(-) plus Del(+) subjects. In the former subjects, non-responders with A1(+) or Del(-) showed higher scores of psychic, extrapyramidal and total side-effects. At therapeutic doses (6-8 mg/day haloperidol equivalent dose) in 30 subjects, the predictability of response was greatly increased (Fisher exact test, P < 0.0045) with higher positive and negative predictive values (78.3% and 85.7%, respectively). These findings suggest that combined DRD(2) polymorphisms can be used as a pretreatment marker for response to DRD(2) antagonists at therapeutic doses, and that A1(+) or Del(-) subjects are highly sensitive to DRD(2) antagonists, expressed as either treatment responders or non-responders vulnerable to extrapyramidal symptoms.
authors.affiliation: Department of Neuropsychiatry, Faculty of Medicine, University of the Ryukyus, Okinawa, Japan. k038705@med.u-ryukyu.ac.jp
authors.forename: Noboru
authors.initials: N
authors.lastname: Sakumoto
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kondo
authors.forename: Kazuo
authors.initials: K
authors.lastname: Mihara
authors.forename: Akihito
authors.initials: A
authors.lastname: Suzuki
authors.forename: Norio
authors.initials: N
authors.lastname: Yasui-Furukori
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000627:therapeutic use; D015415:Biomarkers; D018492:Dopamine Antagonists / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005838:Genotype; D006220:Haloperidol / Q000031:analogs & derivatives / Q000627:therapeutic use; D006801:Humans; D008297:Male; D011110:Polymorphism, Genetic / Q000235:genetics*; D011237:Predictive Value of Tests; D011569:Psychiatric Status Rating Scales; D017448:Receptors, Dopamine D2 / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012559:Schizophrenia / Q000097:blood / Q000188:drug therapy*; D012565:Schizophrenic Psychology
chemical_list: D014150:Antipsychotic Agents; D015415:Biomarkers; D018492:Dopamine Antagonists; D017448:Receptors, Dopamine D2; D006220:Haloperidol; C006820:bromperidol