APOE and Alzheimer disease: An association between the ApoE4 genotype and CSF concentrations of Aβ42 has been described for AD patients and healthy controls, with the ApoE4 allele being associated with lower CSF Aβ42 concentrations in a gene dose-dependent manner (Galasko et al. 1998; Vemuri et al. 2009; Lautner et al. 2014; Konijnenberg et al. 2020).