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


Reviewed September 2008

What is the official name of the TIMM8A gene?

The official name of this gene is “translocase of inner mitochondrial membrane 8 homolog A (yeast).”

TIMM8A is the gene's official symbol. The TIMM8A gene is also known by other names, listed below.

What is the normal function of the TIMM8A gene?

The TIMM8A gene provides instructions for making a protein that is found inside mitochondria, which are structures within cells that convert the energy from food into a form that cells can use. Mitochondria have two membranes, an outer membrane and an inner membrane, which are separated by a fluid-filled area called the intermembrane space. The TIMM8A protein is found in the intermembrane space, where it forms a complex (a group of proteins that work together) with a very similar protein called TIMM13. This complex transports other proteins across the intermembrane space to the mitochondrial inner membrane.

How are changes in the TIMM8A gene related to health conditions?

deafness-dystonia-optic neuronopathy syndrome - caused by mutations in the TIMM8A gene

At least 15 mutations in the TIMM8A gene have been found to cause deafness-dystonia-optic neuronopathy (DDON) syndrome. Most of these mutations result in the absence of functional TIMM8A protein inside the mitochondria, which prevents the formation of the TIMM8A/TIMM13 complex. Researchers believe that the lack of this complex leads to abnormal transport of proteins across the intermembrane space, although it is unclear how abnormal protein transport affects the function of the mitochondria and causes the signs and symptoms of DDON syndrome.

Some people with DDON syndrome have large DNA deletions that remove the entire TIMM8A gene and one end of a neighboring gene known as BTK. Mutations in the BTK gene cause X-linked agammaglobulinemia (XLA), which is characterized by an increased susceptibility to infections. Individuals with large DNA deletions that include the TIMM8A gene and the BTK gene have the signs and symptoms of both DDON syndrome and XLA.

Where is the TIMM8A gene located?

Cytogenetic Location: Xq22.1

Molecular Location on the X chromosome: base pairs 101,345,656 to 101,348,969

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

The TIMM8A gene is located on the long (q) arm of the X chromosome at position 22.1.

The TIMM8A gene is located on the long (q) arm of the X chromosome at position 22.1.

More precisely, the TIMM8A gene is located from base pair 101,345,656 to base pair 101,348,969 on the X chromosome.

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

Where can I find additional information about TIMM8A?

You and your healthcare professional may find the following resources about TIMM8A 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 TIMM8A gene or gene products?

  • DDP
  • DDP1
  • deafness/dystonia peptide
  • DFN1
  • MGC12262
  • translocase of inner mitochondrial membrane 8 homolog A

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

What glossary definitions help with understanding TIMM8A?

DNA ; dystonia ; gene ; mitochondria ; peptide ; protein ; susceptibility ; syndrome

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


  • Binder J, Hofmann S, Kreisel S, Wöhrle JC, Bäzner H, Krauss JK, Hennerici MG, Bauer MF. Clinical and molecular findings in a patient with a novel mutation in the deafness-dystonia peptide (DDP1) gene. Brain. 2003 Aug;126(Pt 8):1814-20. Epub 2003 Jun 4. Review. (
  • Gene Review: Deafness-Dystonia-Optic Neuronopathy Syndrome (
  • Jyonouchi H, Geng L, Törüner GA, Vinekar K, Feng D, Fitzgerald-Bocarsly P. Monozygous twins with a microdeletion syndrome involving BTK, DDP1, and two other genes; evidence of intact dendritic cell development and TLR responses. Eur J Pediatr. 2008 Mar;167(3):317-21. Epub 2007 May 23. (
  • NCBI Gene (
  • Richter D, Conley ME, Rohrer J, Myers LA, Zahradka K, Kelecić J, Sertić J, Stavljenić-Rukavina A. A contiguous deletion syndrome of X-linked agammaglobulinemia and sensorineural deafness. Pediatr Allergy Immunol. 2001 Apr;12(2):107-11. (
  • Roesch K, Curran SP, Tranebjaerg L, Koehler CM. Human deafness dystonia syndrome is caused by a defect in assembly of the DDP1/TIMM8a-TIMM13 complex. Hum Mol Genet. 2002 Mar 1;11(5):477-86. (
  • Roesch K, Hynds PJ, Varga R, Tranebjaerg L, Koehler CM. The calcium-binding aspartate/glutamate carriers, citrin and aralar1, are new substrates for the DDP1/TIMM8a-TIMM13 complex. Hum Mol Genet. 2004 Sep 15;13(18):2101-11. Epub 2004 Jul 14. (
  • Sedivá A, Smith CI, Asplund AC, Hadac J, Janda A, Zeman J, Hansíková H, Dvoráková L, Mrázová L, Velbri S, Koehler C, Roesch K, Sullivan KE, Futatani T, Ochs HD. Contiguous X-chromosome deletion syndrome encompassing the BTK, TIMM8A, TAF7L, and DRP2 genes. J Clin Immunol. 2007 Nov;27(6):640-6. Epub 2007 Sep 12. (


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: September 2008
Published: February 8, 2016