The CYP2D6*1 allele is assigned as a normal function allele by CPIC. Patients carrying the *1 allele in combination with alleles that result in a normal metabolizer phenotype may have a decreased risk of experiencing side effects when treated with imipramine as compared to patients carrying two decreased or no function alleles or a decreased function allele in combination with a no function allele. Other genetic and clinical factors may also influence risk of side effects when treated with imipramine.