Up to 79% of a person's susceptibility to Alzheimer's is determined by a person's genes. Several genetic links have already been traced to Alzheimer's disease. Most notably, the gene APOE was discovered in 1995 and greatly increases a person's risk for the disease. Inheritance of the APOE gene from one parent increases Alzheimer risk by 400%, and from both parents increased risk by 1000%. Today, the APOE gene is the main indicator of Alzheimer's risk when examining a human's genome.
The evidence for the newly discovered genes is substantial, but it is believed these genes only raise risk 10-15%, so they will not be used to decide a person's risk for Alzheimer's. The new genes do present further evidence for the correlation between cholesterol and Alzheimer's disease, as they are involved in cholesterol production in the human body. Doctors and scientists are hopeful that more discoveries like this will help future treatment for the disease, as people susceptible could be treated beforehand to prevent Alzheimer's.
Dr. Schellenberg, a professor at the University of Pennsylvania, led the effort to discover four of the five new genes related to Alzheimer's. Schellenberg believed many genetic studies were being conducted within small, isolated groups. He also believes scientists have been hesitant to share their data and findings with others, and says that this must stop if advances are to be made in the field. For his recent discovery of the new genes, Schellenberg compiled patient data from nearly every Alzheimer's research group in the country. This large sample made the discovery of the genes possible.