The Alzheimer’s disease DNA test will determine whether you carry the APOE e4allele which is associated with an increased lifetime risk of developing late-onset Alzheimer’s disease. It is important to note that individuals who test positive for two copies of APOE e4 are at 10x to 15x increased risk of developing Alzheimer’s Disease, but not all individuals who carry the APOE e4 allele will eventually go on to develop Alzheimer’s disease later in life.
Alleles of APOEThere are three forms or alleles of APOE: APOE e2, APOE e3 and APOE e4. Each person inherits one APOE allele from each parent, so there are six possible combinations of the APOE alleles (e2/e2, e2/e3, e2/e4, e3/e3, e3/e4, e4/e4). The Alzheimer’s disease APOE genotype DNA test identifies the alleles for each person tested and indicates whether or not there is an increased or decreased lifetime risk of developing late-onset Alzheimer’s.
The APOE e2 allele is relatively rare (present in 8.4% of the population) and appears to have a slight protective affect against Alzheimer’s disease. APOE e3 is the most common allele (77.9%) and neither decreases or increases the risk of Alzheimer’s disease. The APOE e4 allele increases the risk of Alzheimer’s disease and is present in 13.7% of the population. Individuals with one copy of the APOE e4 have three times the risk of developing late-onset Alzheimer’s, while those with two copies of APOE e4have 10X to 15X increased lifetime risk of developing Alzheimer’s Disease. However, it is important to note that which having the APOE e4 genotype greatly increases the risk of developing Alzheimer’s Disease, there will be some individuals who have one or more APOE e4 alleles that never get Alzheimer’s Disease and other people who develop Alzheimer’s, despite not having any APOE e4 genes.