APOE and Alzheimer disease: Firstly, APOE genotyping (ɛ2-ɛ3-ɛ4 alleles) was considered as potential biomarker of susceptibility to Hg neurotoxicity in chronically exposed AD patients, with presumptive Hg-related neuropsychiatric symptoms, to identify subjects at greater risk and possibly forestall subsequent neurological deterioration [74].