PSEN2

The PSEN2 gene makes a protein called presenilin 2. The structure and function of this protein are very similar to presenilin 1, which is the protein made by the PSEN1 gene. Presenilin 2 is located in several of the body's tissues, including the brain. It probably plays a role in signaling within cells, turning specific genes on and off, and determining the position of particular proteins within cells. Presenilin 2 is also involved in the processing of a protein called amyloid precursor protein, which has been implicated in the development of Alzheimer disease. Presenilin 2 is thought to help regulate an enzyme that cuts amyloid precursor protein.

Alzheimer disease, type 4 - caused by mutations in the PSEN2 gene

Only a few mutations in PSEN2 have been shown to cause type 4 Alzheimer disease. In particular, a substitution of the amino acid isoleucine for asparagine at position 141 (also written as Asn141Ile) and a change from methionine to valine at position 239 (Met239Val) have been seen in families with type 4 Alzheimer disease. These mutations appear to affect the processing of amyloid precursor protein (a protein found in the brain and other tissues), leading to the increased formation of a protein fragment called amyloid beta peptide. This peptide can form clumps in the brain called amyloid plaques, which are characteristic of Alzheimer disease. Mutations in the PSEN1 and PSEN2 genes are the most common causes of early-onset familial Alzheimer disease.

1q31-q42

The PSEN2 gene is located on the long (q) arm of chromosome 1 between positions 31 and 42.

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

You and your healthcare professional may find the following resources about PSEN2 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

amino acid ; amyloid ; amyloid plaque ; 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.