APOE and Alzheimer disease: The presence of the ε2 allele however, is a protectivefactor against AD.87 Similarallelic and genotypic distribution, besides association of the presence of theε4 allele with AD diagnosis, were also found in population-based andcase-control studies in Brazil.88-92 APOE is involved in cholesteroltransport and formation of the amyloid-β by as yet unknownmechanisms.87Approximately 42% of individuals with AD do not carry the ε4 allele of theAPOE gene.93