What gene mutations are involved in Alzheimers disease?
Three autosomal dominant genes have been identified for early-onset disease. The first one is the amyloid precursor protein (APP) gene, located on chromosome 21. Mutations in the APP gene lead to an increase in the production of amyloid, which is the major component of the plaques that develop in the brains of Alzheimer’s patients. The mutation also results in a more sticky form of amyloid. The other two genes in early-onset disease are called presenilin 1 (PS1) and presenilin 2 (PS2). Mutations in these genes cause them to act as molecular scissors that help cut the amyloid out of the precursor protein. They cut it more rapidly, and they cut it in a form which is more toxic. These mutations account for only perhaps 1 percent of the total number of Alzheimer’s cases, but they gave us very important clues as to where to focus our research. For late-onset Alzheimer’s, the only risk factor gene known right now is ApoE-4. You can have one or two copies, or no copies, of the gene. According
