As reported above, classical HLA typing has been undertaken in the context of clozapine-induced agranulocytosis in the Japanese population20 and others have identified excessive homozygosity in the MHC region of Ashkenazi Jews with schizophrenia, specially in a segment encompassed by TRIM10, TRIM15, and TRIM40. 34 However, the mechanism by which these genes and more broadly the MHC region confer risk for schizophrenia remains largely undetermined. This evidence concerns the gene TRIM15 and Absence of circulating granulocytes.