Paroxetine is a strong inhibitor of CYP2D6 (http://www.fda.gov/Drugs/DevelopmentApprovalProcess/DevelopmentResources/DrugInteractionsLabeling/ucm093664.htm#cypEnzymes) and is the most likely AD to exert a negative influence on the outcome of tamoxifen therapy (Borges et al., 2006; Kelly et al., 2010). The gene discussed is CYP2D6; the disease is Alzheimer disease.