HLA-B38 and clozapine-induced agranulocytosis in Israeli Jewish schizophrenic patients

To further substantiate reports of an association between the major histocompatibility complex subtypes and clozapine‐induced agranulocytosis, HLA typing was performed in 61 Jewish Israeli schizophrenic patients, in 11 of whom agranulocytosis developed following clozapine treatment and in 50 (controls) of whom it did not. Of the 11 agranulocytosis patients, seven (63%) were of Ashkenazi origin and four (37%) of Sephardi origin. There was no difference in ethnic origin between the agranulocytosis and non‐agranulocytosis groups (χ2 = 2.4, d.f. = 1, P = 0.11), although the agranulocytosis patients had a higher frequency of the HLA B38 antigen (8/11 or 72% vs. 6/50 or 12%; χ2 = 18.7, d.f. = 1, P < 0.001). These results suggest that major histocompatibility complex gene products could be involved in clozapine‐mediated haematological complications.