The APOE ε3 allele is considered the most common and neutral variant in the context of AD, as it has been shown to neither increase nor decrease the risk influence of disease onset.48-51 The finding that APOE3/3 carriers have greater brain asymmetry suggests that genetic pre-disposition plays a crucial role in shaping the loss of symmetry of individuals even before symptoms of AD appear. The gene discussed is APOE; the disease is Alzheimer disease.