PSEN1

The PSEN1 gene makes a protein called presenilin 1. This protein is very similar in structure and function to presenilin 2, which is the protein made by the PSEN2 gene. Presenilin 1 is located in many tissues in the body, including the brain. Presenilin 1 probably has several functions, such as signaling within cells, turning certain genes on and off, and determining the position of particular proteins within cells. It is also involved in the processing of a protein called amyloid precursor protein, which has been implicated in Alzheimer disease. Although researchers do not yet know the exact role of presenilin 1, they believe that it regulates an enzyme that cuts amyloid precursor protein.

Alzheimer disease, type 3 - caused by mutations in the PSEN1 gene

More than 130 PSEN1 mutations have been identified in patients with type 3 Alzheimer disease. Almost all of these mutations are substitutions of one DNA base (the building blocks of DNA) for another in a particular segment of the PSEN1 gene, resulting in an altered presenilin 1 protein. Defective presenilin 1 affects the processing of amyloid precursor protein (a protein found in the brain and other tissues), which leads to increased production of a protein fragment called amyloid beta peptide. This peptide can build up in the brain to form clumps called amyloid plaques, which are characteristic of Alzheimer disease. Mutations in the PSEN1 gene and the very similar PSEN2 gene are the most common causes of early-onset familial Alzheimer disease.

14q24.3

The PSEN1 gene is located on the long (q) arm of chromosome 14 at position 24.3.

See How do geneticists indicate the location of a gene? in the Handbook.

You and your healthcare professional may find the following resources about PSEN1 helpful.

• Gene Reviews - Clinical summary
• Gene Tests - DNA tests ordered by healthcare professionals

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

• PubMed - Recent literature
• OMIM - Genetic disorder catalog
• Research Resources - Tools for researchers (4 links)

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

The Handbook provides basic information about genetics in clear language.

• What is DNA?
• What is a gene?
• How does a gene make a protein?
• How can gene mutations cause disorders?

These links provide additional genetics resources that may be useful.

• Genetics education
• Human Genome Project
• Resources for Genetic Researchers

amyloid ; amyloid plaque ; DNA ; DNA base ; enzyme ; familial ; gene ; gene product ; isoforms ; mutation ; peptide ; protein ; substitution

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