Variation in the APOE gene is the strongest genetic factor influencing the risk of late-onset AD. This gene encodes apolipoprotein E, which is involved in transporting fats, neuronal growth, nerve regeneration, immunoregulation and injury repair in the central nervous system.
There are three common variants (alleles) of APOE, known as e2, e3 and e4. Each of us inherits two copies of the APOE gene. The APOE genotype indicates our risk of late-onset AD:
- e2/e2 – reduced risk
- e2/e3 – reduced risk
- e2/e4 – 3X increased risk
- e3/e3 – does not affect your risk
- e3/e4 – 3X increased risk
- e4/e4 – 10X to 15X increased risk