It is well established that the APOE gene, particularly the ε4 allele, is the most potent genetic risk factor for late-onset AD [6, 7, 9, 36] and is also associated with an increased risk and severity of adverse effects, specifically ARIA, in patients undergoing anti-amyloid therapies, such as monoclonal antibodies against amyloid-beta (Aβ) [10]. The gene discussed is APOE; the disease is Alzheimer disease.