APOE and Alzheimer disease: In two phase III trials of bapineuzumab, some patients who met the criteria (McKhann et al. 1984) of probable AD did not reach the positive threshold for amyloid-positive category (6.5% of carriers of the apolipoprotein E (APOE) ε4 allele, 36.1% of noncarriers) (Salloway et al. 2014), suggesting that the clinical diagnosis is unreliable to identify underlying pathology, especially when the care-providing physicians are general practitioners rather than dementia specialists.