Additionally, we examine antipsychotics, including clozapine and newer agents like aripiprazole, brexpiprazole, and cariprazine, highlighting specific gene-drug interactions and known risk alleles such as HLA-B*15:02, HLA-A*31:01, and variants in CYP2D6 and CYP1A2. These findings underscore the value of pharmacogenomic testing in predicting and preventing serious DHRs, such as Stevens-Johnson Syndrome, toxic epidermal necrolysis, agranulocytosis, and hepatotoxicity. The gene discussed is HLA-B; the disease is Absence of circulating granulocytes.