Alzheimer disease, type 2

Alzheimer disease, type 2 is a late-onset familial form of Alzheimer disease. This degenerative disease of the brain causes gradual loss of memory, judgment, and ability to function socially.

Alzheimer disease, type 2 is a subtype of Alzheimer disease.

The major signs of this condition are progressive brain deterioration after age 65 years, leading to a gradual loss of memory, reasoning, and ability to perform social and personal care functions. Please see the Alzheimer disease summary for further information about the symptoms of this disorder.

About 25 percent of all people with Alzheimer disease have a late-onset, familial form of the disorder. The other 75 percent of cases are classified as sporadic, and the cause of these cases remains unknown.

Variations of the APOE gene increase the risk of developing Alzheimer disease, type 2.

This condition is probably caused by mutations in a gene or genes that have not yet been identified. However, researchers have found that a gene called apolipoprotein E (APOE) can affect a person's risk of developing type 2 Alzheimer disease. In particular, a form of APOE called the epsilon 4 (or e4) allele has been shown to increase the chances of developing the disease.

People with the APOE e4 allele inherit an increased risk of Alzheimer disease, not the disease itself. Not all people with Alzheimer disease have the e4 allele, and not all people who have the e4 allele will develop the disease. People who inherit one copy of the APOE e4 allele are at increased risk, while people who inherit two copies of APOE e4 have the highest chance of developing the disease.

You may find the following resources about Alzheimer disease, type 2, helpful.

• NIH Publications - National Institutes of Health (2 links)
• MedlinePlus - Health Information (2 links)
• Genes and Disease - Genetic disorder summaries
• Patient support - For patients and families (4 links)

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

• Gene Reviews - Clinical summary
• ClinicalTrials.gov - Linking patients to medical research
• PubMed - Recent literature
• OMIM - Genetic disorder catalog

See How are genetic conditions and genes named? in the Handbook.

The Handbook provides basic information about genetics in clear language.

• What does it mean if a disorder seems to run in my family?
• What are the different ways in which a genetic condition can be inherited?
• If a genetic disorder runs in my family, what are the chances that my children will have the condition?
• Why are some genetic conditions more common in particular ethnic groups?

These links provide additional genetics resources that may be useful.

• Genetics and health
• Resources for Patients and Families
• Resources for Health Professionals

allele ; amyloid ; amyloid plaque ; degenerative ; dementia ; familial ; gene ; mutation ; peptide ; sign ; sporadic ; symptom

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.