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Genetic and Rare Diseases Information Center (GARD)

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Alzheimer disease type 1

Other Names for this Disease
  • AD1
  • Alzheimer disease 1
  • Early-onset familial form of Alzheimer disease
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Your Question

I once heard that Alzheimers Disease skips generations.  For example, my mother's father suffered from this illness. Does my mother have a higher chance of developing the condition than my brother and I?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What is Alzheimer disease?

Alzheimer disease is a degenerative disease of the brain that causes gradual loss of memory, judgment, and ability to function socially. Alzheimer disease currently affects about 5 million people.[1] About 75 percent of Alzheimer disease cases are classified as sporadic, which means they occur in people with no history of the disorder in their family. Although the cause of these cases is unknown, genetic changes are likely to play a role. Virtually all sporadic Alzheimer disease begins after age 65, and the risk of developing this condition increases as a person gets older.

The remaining cases of Alzheimer disease are familial, which means they are found in multiple members of a family. Familial Alzheimer disease can be divided into early-onset disease (symptoms begin before age 65) and late-onset disease (symptoms begin after age 65).[2]

Last updated: 7/2/2013

Can you tell me my chances of developing Alzheimers disease?

No, only your personal health care provider can address your and your family's specific risks. However we have provided general information about the inheritance of Alzheimer disease in the questions and answers below. To learn about the risks specific to you and your family, we recommend that you speak with a genetics professional. A genetics professional can carefully review your family history to answer your specific questions. More information on how to find a genetics professional is available from the Genetics Home Reference at
Last updated: 7/5/2013

Can Alzheimer disease be passed through families?

About 75% of Alzheimer disease cases are classified as sporadic, which means that no other blood relatives are affected. The cause of these cases is not known at this time, but genetics may play a part. The risk of developing the condition increases as a person gets older.

The remaining 25 percent of Alzheimer disease cases are hereditary, which means they are caused by mutated genes and tend to cluster in families. These cases can be divided into early-onset disease and late-onset disease.[1]
Last updated: 7/2/2013

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

What is late-onset Alzheimer disease and how is it inherited?

Late-onset Alzheimer disease is a form of Alzheimer disease that begins to affect people after the age of 65. The genetic causes of late-onset Alzheimer disease are less clear. No gene that definitely causes the condition has been identified. However, a gene called APOE has been studied extensively as a risk factor for the disease. In particular, one form (or allele) of this gene seems to increase an individual's risk for developing type 2 Alzheimer disease. [3]
Last updated: 7/5/2013

How can I find a genetics professional in my area?

Genetics clinics are a source of information for individuals and families regarding genetic conditions, treatment, inheritance, and genetic risks to other family members. More information about genetic consultations is available from Genetics Home Reference. To find a genetics clinic, we recommend that you contact your primary healthcare provider for a referral.

The following online resources can help you find a genetics professional in your community:
Last updated: 10/18/2013