Individuals with significant valvular heart disease, history of myocardial infarction, prior coronary revascularization, or stable angina, as well as those with baseline LVEF < 50% or age ≥ 80 years, and individuals with pre-existing heart failure or cardiomyopathy are considered respectively at high and very high risk for cardiotoxicity prior to starting anthracycline or human epidermal growth factor receptor 2 (HER2)-targeted therapies. The gene discussed is ERBB2; the disease is cardiomyopathy.