Test Details: The Apolipoprotein (Apo) E is one of the five main types of blood lipoprotein (A-E) and is produced by APOE gene. APOE gene exists in three different forms (alleles) - e2, e3 and e4; where e4 genotype is a genetic risk factor for dementia, Alzheimer's disease (AD) and cardiovascular disease. For example, if a person has dementia, the presence of APOE e4 allele may increase the chances that the dementia is due to AD.