No direct clinical relevance of the human leucocyte antigen (HLA) system in clozapine-induced agranulocytosis.

The clinical use of clozapine in psychiatry is restricted by the associated risk of agranulocytosis. This risk is significantly higher than that associated with conventional antipsychotic medications. In order to identify a possible parameter to detect susceptible individuals before treatment, 103 patients with a history of clozapine-induced granulocytopenia or agranulocytosis and 95 matched control patients were typed for human leucocyte antigen (HLA)-A, -B, -C, -DR, -DQ and for a number of neutrophil-specific alloantigens. No significant association between certain HLA alleles or neutrophil antigens and susceptibility to clozapine-induced granulocytopenia or agranulocytosis was observed.