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Genetic and Rare Diseases Information Center (GARD)

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Alzheimer disease type 3

Other Names for this Disease
  • AD3
  • Alzheimer disease 3
  • Alzheimer disease early onset type 3
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What is early-onset Alzheimer disease and how is it inherited?

Early-onset Alzheimer disease is a form of Alzheimer disease that begins to affect people before the age of 65. Fewer than 2% of families with Alzheimer disease have early-onset familial Alzheimer disease. Researchers have identified three genes that cause early-onset familial Alzheimer disease, the amyloid beta precursor protein (APP) gene, presenilin 1 (PSEN1) gene, and presenilin 2 (PSEN2) gene. In general, most individuals diagnosed as having early-onset Alzheimer disease have had an affected parent.

Early-onset Alzheimer disease is often inherited in an autosomal dominant manner, meaning that the risk to offspring of an individual with early-onset familial Alzheimer disease is 50% if a mutation is found in APP, PSEN1, or PSEN2. Occasionally, neither parent is affected, but a second-degree relative (e.g., an uncle, aunt and/or grandparent) has or had early-onset Alzheimer disease.

You can read a comprehensive review of early-onset Alzheimer disease on the GeneReviews Web site.
Last updated: 7/5/2013