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The official name of this gene is “ataxin 3.”
ATXN3 is the gene's official symbol. The ATXN3 gene is also known by other names, listed below.
The ATXN3 gene provides instructions for making an enzyme called ataxin-3, which is found in cells throughout the body. Ataxin-3 is involved in a mechanism called the ubiquitin-proteasome system that destroys and gets rid of excess or damaged proteins. The molecule ubiquitin attaches (binds) to unneeded proteins and tags them to be broken down (degraded) within cells. Ataxin-3 removes (cleaves) the ubiquitin from these unwanted proteins just before they are degraded so that the ubiquitin can be used again. Due to its role in cleaving ubiquitin from proteins, ataxin-3 is known as a deubiquitinating enzyme.
Researchers believe that ataxin-3 also may be involved in regulating the first stage of protein production (transcription).
Spinocerebellar ataxia type 3 (SCA3) is a condition characterized by progressive problems with movement. SCA3 results from a mutation in the ATXN3 gene known as a trinucleotide repeat expansion. This mutation increases the length of the repeated CAG segment in the ATXN3 gene. People with SCA3 have more than 50 CAG repeats.
The expanded CAG segment leads to the production of an abnormally long version of the ataxin-3 protein that folds into the wrong 3-dimensional shape. This nonfunctional ataxin-3 protein cannot remove ubiquitin from proteins that are no longer needed. As a result, these unwanted proteins, along with ubiquitin and ataxin-3, cluster together to form clumps (aggregates) within the nucleus of the cells. It is unclear how these aggregates affect cell function, because they are found in healthy cells as well as those that die.
Nerve cells (neurons) and other types of brain cells are most affected by mutations in the ATXN3 gene. SCA3 is associated with cell death in the part of the brain that is connected to the spinal cord (the brainstem), the part of the brain involved in coordinating movements (the cerebellum), and other areas of the brain. This condition is also associated with the death of neurons in the spinal cord. Over time, the loss of cells in the brain and spinal cord cells cause the signs and symptoms characteristic of SCA3.
Cytogenetic Location: 14q21
Molecular Location on chromosome 14: base pairs 92,058,551 to 92,106,620
The ATXN3 gene is located on the long (q) arm of chromosome 14 at position 21.
More precisely, the ATXN3 gene is located from base pair 92,058,551 to base pair 92,106,620 on chromosome 14.
See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genelocation) in the Handbook.
You and your healthcare professional may find the following resources about ATXN3 helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
ataxia ; brainstem ; cell ; cerebellum ; enzyme ; gene ; molecule ; mutation ; nucleus ; proteasome ; protein ; stage ; transcription ; trinucleotide repeat ; ubiquitin
You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.ghr.nlm.nih.gov/glossary).
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.