Genes and Alzheimer disease
Most people with Alzheimer disease have not inherited it. However, in a few cases (less than one in 100), Alzheimer disease is inherited from an affected parent (familial Alzheimer disease). In this type of Alzheimer's the symptoms tend to appear earlier than usual. Scientists have identified several genes that are altered in familial Alzheimer disease. Researchers have also found a version of another gene, called APOE4, which is associated with an increased risk of Alzheimer disease in non-familial cases.