It’s believed that inherited genes account for about 70 percent of the risk for developing Alzheimer’s disease. A gene called APOE4 is a major genetic risk factor for Alzheimer’s disease. About 20-24 percent of the population carry one copy of this gene (inherited from one parent) and about 2-3 percent of the population have two copies of this gene (inherited from both parents). Each additional copy of the APOE4 gene increases a person’s chance of developing the disease.
So far, researchers have identified about 10 other “Alzheimer’s susceptibility genes,” and they’re working collaboratively to identify more.
In addition, three inherited genes – PS1, PS2 and APP – are known to cause people to develop Alzheimer’s disease while in their 30s, 40s or 50s. Individuals who inherit one of these genetic mutations are virtually certain to develop early-onset Alzheimer’s, and their children have a 50/50 chance of inheriting the same gene.