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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed April 2015

What is the official name of the APTX gene?

The official name of this gene is “aprataxin.”

APTX is the gene's official symbol. The APTX gene is also known by other names, listed below.

What is the normal function of the APTX gene?

The APTX gene provides instructions for making a protein called aprataxin that is involved in the repair of damaged DNA or RNA, the chemical cousin of DNA. Aprataxin is located in the nucleus of cells and is produced in various tissues, including the brain, spinal cord, and muscles. Different regions of the aprataxin protein aid in its DNA or RNA repair function by allowing the protein to interact with other DNA repair proteins and to attach (bind) to DNA or RNA molecules. At the site of damage, aprataxin modifies the broken ends of the DNA or RNA strands so they can be joined back together.

How are changes in the APTX gene related to health conditions?

ataxia with oculomotor apraxia - caused by mutations in the APTX gene

At least 30 mutations in the APTX gene have been found to cause ataxia with oculomotor apraxia type 1. This condition is characterized by difficulty coordinating movements (ataxia) and problems with side-to-side movements of the eyes (oculomotor apraxia). Most mutations change single protein building blocks (amino acids) in aprataxin, resulting in an unstable aprataxin protein that is quickly broken down in the cell. A lack of functional aprataxin disrupts DNA repair and can lead to an accumulation of DNA damage in cells, particularly affecting brain cells in the part of the brain involved in coordinating movements (the cerebellum). This accumulation can lead to cell death in the cerebellum, causing the characteristic movement problems of ataxia with oculomotor apraxia type 1.

Where is the APTX gene located?

Cytogenetic Location: 9p13.3

Molecular Location on chromosome 9: base pairs 32,972,606 to 33,025,138

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The APTX gene is located on the short (p) arm of chromosome 9 at position 13.3.

The APTX gene is located on the short (p) arm of chromosome 9 at position 13.3.

More precisely, the APTX gene is located from base pair 32,972,606 to base pair 33,025,138 on chromosome 9.

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

Where can I find additional information about APTX?

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

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

What other names do people use for the APTX gene or gene products?

  • AOA
  • AOA1
  • ataxia 1, early onset with hypoalbuminemia
  • AXA1
  • EAOH

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

What glossary definitions help with understanding APTX?

acids ; apraxia ; ataxia ; cell ; cerebellum ; DNA ; DNA damage ; DNA repair ; gene ; nucleus ; protein ; RNA

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


  • Hirano M, Asai H, Kiriyama T, Furiya Y, Iwamoto T, Nishiwaki T, Yamamoto A, Mori T, Ueno S. Short half-lives of ataxia-associated aprataxin proteins in neuronal cells. Neurosci Lett. 2007 May 29;419(2):184-7. Epub 2007 Apr 25. (
  • Le Ber I, Moreira MC, Rivaud-Péchoux S, Chamayou C, Ochsner F, Kuntzer T, Tardieu M, Saïd G, Habert MO, Demarquay G, Tannier C, Beis JM, Brice A, Koenig M, Dürr A. Cerebellar ataxia with oculomotor apraxia type 1: clinical and genetic studies. Brain. 2003 Dec;126(Pt 12):2761-72. Epub 2003 Sep 23. (
  • NCBI Gene (
  • Rass U, Ahel I, West SC. Actions of aprataxin in multiple DNA repair pathways. J Biol Chem. 2007 Mar 30;282(13):9469-74. Epub 2007 Feb 2. (
  • Tada M, Yokoseki A, Sato T, Makifuchi T, Onodera O. Early-onset ataxia with ocular motor apraxia and hypoalbuminemia/ataxia with oculomotor apraxia 1. Adv Exp Med Biol. 2010;685:21-33. Review. (
  • Takahashi T, Tada M, Igarashi S, Koyama A, Date H, Yokoseki A, Shiga A, Yoshida Y, Tsuji S, Nishizawa M, Onodera O. Aprataxin, causative gene product for EAOH/AOA1, repairs DNA single-strand breaks with damaged 3'-phosphate and 3'-phosphoglycolate ends. Nucleic Acids Res. 2007;35(11):3797-809. Epub 2007 May 22. (
  • Tumbale P, Williams JS, Schellenberg MJ, Kunkel TA, Williams RS. Aprataxin resolves adenylated RNA-DNA junctions to maintain genome integrity. Nature. 2014 Feb 6;506(7486):111-5. doi: 10.1038/nature12824. Epub 2013 Dec 22. (


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? ( in the Handbook.

Reviewed: April 2015
Published: February 8, 2016