HLA-DRB1 and Absence of circulating granulocytes: Certain HLA alleles, such as HLA-DRB1*04:02, HLA-DPB1*05:02, HLA-DQB1 (126Q), HLA-B (158T), and HLA-B*59:01, have been reported to be associated with clozapine-induced agranulocytosis (116–118).