We identified a novel candidate region for APOE4 carriers on 4p15.1 (33.6Mb-34.3Mb), which, according to the GWAS catalogue (https://www.ebi.ac.uk/gwas/) has not been previously associated with AD, but with schizophrenia, total cholesterol change in response to fenofibrate in statin-treated type 2 diabetes, and PCSK9 levels, a protease that binds to lipoprotein receptors promoting their degradation; a homozygous deletion overlapping this region has been described for the offspring of a consanguineous marriage between first cousins, with cognitive impairment and autistic-like behavior [27]. This evidence concerns the gene PCSK9 and Cognitive impairment.