The ApoE gene provides instructions for making a protein called apolipoprotein E. In the brain, ApoE is involved in clearing harmful plaques that form around nerve cells. These plaques are a hallmark of Alzheimer’s disease and consist of damaged proteins called amyloid β which stick together to form the toxic plaques. There are at least three slightly different versions (alleles) of the ApoE gene. The major alleles are called E2, E3, and E4. The most common allele is E3, which is found in more than half of the general population. The E2 form is the most effective at removing Aβ plaque from the brain and subsequently is protective against Alzheimer’s disease. However, the E4 form of the ApoE protein is not very effective at removing Aβ plaque and carries an increased risk for developing Alzheimer’s disease.
ApoE combines with fats (lipids) in the body to form molecules called lipoproteins. Lipoproteins are responsible for packaging cholesterol and other fats and carrying them through the bloodstream. Maintaining normal levels of cholesterol is essential for the prevention of disorders that affect the heart and blood vessels (cardiovascular diseases), including heart attack and stroke. The ApoE test report includes results and comments related to both Cardiovascular and Alzheimer’s disease risk.