Original ArticlesFurther evidence of human leukocyte antigen-encoded susceptibility to clozapine-induced agranulocytosis independent of ancestryDettling, M.a,b; Schaub, R. T.c; Mueller-Oerlinghausen, B.d; Roots, I.e; Cascorbi, I.e,fAuthor Information aDepartment of Psychiatry, University Hospital Benjamin Franklin, Free University of Berlin, bDepartment of Psychiatry, University Hospital Charité, Humboldt University Berlin, cDepartment of Psychiatry, Ernst Moritz Arndt University Greifswald, dDrug Commission of the German Medical Association, Cologne, eInstitute of Clinical Pharmacology, University Hospital Charité, Humboldt University, Berlin and fInstitute of Pharmacology, Ernst Moritz Arndt University Greifswald, Germany Received 13 April 2000; accepted 09 September 2000 Correspondence to Michael Dettling, Department of Psychiatry, University Hospital Charité, Humboldt University, Schumannstrasse 20/21, D-10117 Berlin, Germany Tel: +49 30 2802 4409/4590; e-mail: [email protected] Pharmacogenetics: March 2001 - Volume 11 - Issue 2 - p 135-141 Buy Abstract To further examine the human leukocyte antigen (HLA)-encoded genetic susceptibility to clozapine-induced agranulocytosis (CA) we performed HLA-genotyping in a sample of German schizophrenic patients, who suffered from this haematotoxic side-effect. Thirty-one schizophrenic patients with CA (17 women and 14 men) and 77 schizophrenic comparison subjects (40 women and 37 men) were included in the study. HLA-genotyping included identification of major histocompatibility complex (MHC) class I (HLA-A, B, Cw) and class II (HLA-DR, DQ) antigens. CA was significantly associated with HLA-Cw*7 (P < 0.02), DQB *0502 (P < 0.04), DRB1 *0101 (P < 0.03) and DRB3 *0202 (P < 0.02). These HLA-haplotypes are also partly linked to other diseases with a strong genetic background. All other antigens revealed no association to this haematotoxic reaction. In addition, we did not find gender-related effects, whereas age seemed to be a further major risk factor of CA (P < 0.0003). Thus, HLA loci may serve as genetic marker to identify subjects of different ethnic subgroups prone to this severe idiosyncratic drug reaction of clozapine. Further studies are needed to investigate whether these associations with CA are due to causal involvement or linkage disequilibrium. © 2001 Lippincott Williams & Wilkins, Inc.