An association between clozapine-induced agranulocytosis in schizophrenics and HLA-DQB1*0201

A group of 18 Israeli, clozapine-treated, schizophrenia patients underwent molecular and serological HLA typing in order to determine whether the major histocompatibility complex is associated with the development of clozapine-induced agranulocytosis. While under treatment with clozapine, 2 of the 18 patients developed agranulocytosis (total white blood cell count < 3000/mm(3) and absolute polymorphonuclear count < 500/mm(3)) and 3 developed granulocytopenia (total white blood cell count < 3500/mm(3) and absolute polymorphonuclear count < 1000/mm(3)). HLA-DQBI*0201 was present in all Eve patients who developed agranulocytosis or granulocytopenia (5/5; 100%), but in only 54% (7/13) of the patients who did not develop those complications. These findings indicate that DQBI*0201 or a gene located nearby could be involved in clozapine-induced agranulocytosis.