Additionally, a correlation was revealed between clozapine-induced somnolence and rs2737385 polymorphism on HNMT gene, rs1552498 and rs17034063 polymorphisms on HRH1 gene (Histamine Receptor H1), as well as rs697738 polymorphism on AOC1 gene (Amine Oxidase Copper Containing 1). This evidence concerns the gene HRH1 and Coma.