APOE and Alzheimer disease: The ε4 allele of APOE alters lipid metabolism regulation and cholesterol transport and known to be a major genetic risk determinant for sporadic, late-onset Alzheimer’s disease14 and Lewy body dementia.7,9 Dose effects by allele have demonstrated a 3.7-fold risk of developing AD while homozygosity increases the risk by up to 12-fold.7 From numerous GWASs, APOE does not alter the risk for PD, yet the ε4 allele has been described as a potential risk factor for cognitive decline and development of dementia in PD patients.15,16