The most common gene associated with late-onset Alzheimer’s disease is called apolipoprotein E (APOE). APOE has three common forms:
APOE e2 — the least common — reduces the risk of Alzheimer’s.
APOE e4 — a little more common — increases the risk of Alzheimer’s and is associated with getting the disease at an earlier age. Approximately 15% to 25% of the general population carries an APOE e4 allele.
APOE e3 — the most common — doesn’t seem to affect the risk of Alzheimer’s
You inherit two APOE genes, one from each parent. Having at least one APOE e4 gene increases your risk of developing Alzheimer’s disease by 200-300%. If you have two APOE e4 genes, your risk is even higher, approximately 800-1200%.
Researchers estimate that between 40-65% of people diagnosed with Alzheimer’s have the APOE-e4 gene, but not everyone who has one or even two APOE e4 genes develops Alzheimer’s disease. Other genetic and environmental factors are involved in the development of Alzheimer’s disease.
Other genes which are risk indicators for Alzheimer’s are:
CLU – This gene helps regulate the clearance of amyloid-beta from the brain. Amyloid-beta plaques are one of the main causes of neuronal cell death in Alzheimer’s.
ABCA7 – Researchers suspect that this may have something to do with the gene’s influence on how the body uses cholesterol.
CR1 – A deficiency of the protein this gene produces may contribute to chronic inflammation in the brain.
PLD3 – Scientists are not quite sure what this gene does, but it’s appearance is correlated with an increased risk.
TREM2 – This gene helps regulate the brain’s response to inflammation.