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


Reviewed November 2006

What is the official name of the SLC25A15 gene?

The official name of this gene is “solute carrier family 25 (mitochondrial carrier; ornithine transporter) member 15.”

SLC25A15 is the gene's official symbol. The SLC25A15 gene is also known by other names, listed below.

What is the normal function of the SLC25A15 gene?

The SLC25A15 gene provides instructions for making a protein called a mitochondrial ornithine transporter. This transporter protein is needed for the urea cycle, a series of reactions that occurs in liver cells. The urea cycle processes excess nitrogen, generated when protein is used by the body, into a compound called urea that is excreted by the kidneys. Excreting the excess nitrogen prevents it from accumulating in the form of ammonia, which is toxic, especially to the nervous system.

The mitochondrial ornithine transporter protein moves a molecule called ornithine within the mitochondria (the energy-producing centers in cells). Specifically, this protein transports ornithine across the inner membrane of mitochondria to the region called the mitochondrial matrix, where it participates in the urea cycle.

Does the SLC25A15 gene share characteristics with other genes?

The SLC25A15 gene belongs to a family of genes called SLC (solute carriers).

A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? ( in the Handbook.

How are changes in the SLC25A15 gene related to health conditions?

ornithine translocase deficiency - caused by mutations in the SLC25A15 gene

Approximately 17 mutations in the SLC25A15 gene have been identified in individuals affected by ornithine translocase deficiency. The mutations result in a mitochondrial ornithine transporter that is unstable, the wrong shape, or otherwise lacking the ability to bring ornithine to the mitochondrial matrix. This failure of ornithine transport causes an interruption of the urea cycle and the accumulation of ammonia, resulting in the signs and symptoms of ornithine translocase deficiency.

Where is the SLC25A15 gene located?

Cytogenetic Location: 13q14

Molecular Location on chromosome 13: base pairs 40,789,411 to 40,812,460

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

The SLC25A15 gene is located on the long (q) arm of chromosome 13 at position 14.

The SLC25A15 gene is located on the long (q) arm of chromosome 13 at position 14.

More precisely, the SLC25A15 gene is located from base pair 40,789,411 to base pair 40,812,460 on chromosome 13.

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

Where can I find additional information about SLC25A15?

You and your healthcare professional may find the following resources about SLC25A15 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 SLC25A15 gene or gene products?

  • D13S327
  • HHH
  • ORC1
  • ornithine transporter 1
  • ORNT1
  • OTTHUMP00000042249

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

What glossary definitions help with understanding SLC25A15?

ammonia ; carrier ; compound ; deficiency ; gene ; mitochondria ; molecule ; nervous system ; protein ; solute ; toxic ; urea

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


  • Camacho JA, Mardach R, Rioseco-Camacho N, Ruiz-Pesini E, Derbeneva O, Andrade D, Zaldivar F, Qu Y, Cederbaum SD. Clinical and functional characterization of a human ORNT1 mutation (T32R) in the hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome. Pediatr Res. 2006 Oct;60(4):423-9. Epub 2006 Aug 28. (
  • Camacho JA, Obie C, Biery B, Goodman BK, Hu CA, Almashanu S, Steel G, Casey R, Lambert M, Mitchell GA, Valle D. Hyperornithinaemia-hyperammonaemia-homocitrullinuria syndrome is caused by mutations in a gene encoding a mitochondrial ornithine transporter. Nat Genet. 1999 Jun;22(2):151-8. (
  • Camacho JA, Rioseco-Camacho N, Andrade D, Porter J, Kong J. Cloning and characterization of human ORNT2: a second mitochondrial ornithine transporter that can rescue a defective ORNT1 in patients with the hyperornithinemia-hyperammonemia-homocitrullinuria syndrome, a urea cycle disorder. Mol Genet Metab. 2003 Aug;79(4):257-71. (
  • Korman SH, Kanazawa N, Abu-Libdeh B, Gutman A, Tsujino S. Hyperornithinemia, hyperammonemia, and homocitrullinuria syndrome with evidence of mitochondrial dysfunction due to a novel SLC25A15 (ORNT1) gene mutation in a Palestinian family. J Neurol Sci. 2004 Mar 15;218(1-2):53-8. (
  • Miyamoto T, Kanazawa N, Hayakawa C, Tsujino S. A novel mutation, P126R, in a Japanese patient with HHH syndrome. Pediatr Neurol. 2002 Jan;26(1):65-7. (
  • Miyamoto T, Kanazawa N, Kato S, Kawakami M, Inoue Y, Kuhara T, Inoue T, Takeshita K, Tsujino S. Diagnosis of Japanese patients with HHH syndrome by molecular genetic analysis: a common mutation, R179X. J Hum Genet. 2001;46(5):260-2. (
  • NCBI Gene (
  • Palmieri F. The mitochondrial transporter family (SLC25): physiological and pathological implications. Pflugers Arch. 2004 Feb;447(5):689-709. Epub 2003 Nov 4. Review. (
  • Salvi S, Dionisi-Vici C, Bertini E, Verardo M, Santorelli FM. Seven novel mutations in the ORNT1 gene (SLC25A15) in patients with hyperornithinemia, hyperammonemia, and homocitrullinuria syndrome. Hum Mutat. 2001 Nov;18(5):460. (
  • Salvi S, Santorelli FM, Bertini E, Boldrini R, Meli C, Donati A, Burlina AB, Rizzo C, Di Capua M, Fariello G, Dionisi-Vici C. Clinical and molecular findings in hyperornithinemia-hyperammonemia-homocitrullinuria syndrome. Neurology. 2001 Sep 11;57(5):911-4. (
  • Torisu H, Kira R, Kanazawa N, Takemoto M, Sanefuji M, Sakai Y, Tsujino S, Hara T. A novel R275X mutation of the SLC25A15 gene in a Japanese patient with the HHH syndrome. Brain Dev. 2006 Jun;28(5):332-5. Epub 2006 Jan 10. (
  • Tsujino S, Kanazawa N, Ohashi T, Eto Y, Saito T, Kira J, Yamada T. Three novel mutations (G27E, insAAC, R179X) in the ORNT1 gene of Japanese patients with hyperornithinemia, hyperammonemia, and homocitrullinuria syndrome. Ann Neurol. 2000 May;47(5):625-31. (


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: November 2006
Published: February 1, 2016