In light of the new biological disease-modifying therapies targeting amyloid-beta (Aβ), such as aducanumab [12, 42], lecanemab [43, 44], and donanemab [11, 45], determining the APOE ε4 carrier status has become an essential component of the diagnostic and therapeutic work-up in AD [46, 47]. The gene discussed is APOE; the disease is Alzheimer disease.