HLA-B and Absence of circulating granulocytes: The occurrence of clozapine-induced agranulocytosis is associated with older age and the presence of certain HLA gene variants (e.g. HLA-B38, DRB1*0402, DRB4*0101, DQB1*0302, HLA-DQB1, HLA-B (Yunis et al., 1995; Legge and Walters, 2019), which could explain regional incidence differences.