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


Reviewed July 2006

What is the official name of the SLC22A5 gene?

The official name of this gene is “solute carrier family 22 (organic cation/carnitine transporter), member 5.”

SLC22A5 is the gene's official symbol. The SLC22A5 gene is also known by other names, listed below.

What is the normal function of the SLC22A5 gene?

The SLC22A5 gene provides instructions for making a protein called OCTN2 that is found in the heart, liver, muscles, kidneys, and other tissues. This protein is positioned within the cell membrane, where it transports a substance known as carnitine into the cell. Carnitine is mainly obtained from the diet and is needed to bring certain types of fats (fatty acids) into mitochondria, the energy-producing centers within cells. Fatty acids are a major source of energy for the heart and muscles. During periods without food (fasting), fatty acids are also an important energy source for the liver and other tissues.

Does the SLC22A5 gene share characteristics with other genes?

The SLC22A5 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 SLC22A5 gene related to health conditions?

primary carnitine deficiency - caused by mutations in the SLC22A5 gene

More than 60 mutations in the SLC22A5 gene have been found to cause primary carnitine deficiency. Some of these mutations create a premature stop signal in the instructions for making the OCTN2 protein, resulting in an abnormally short, nonfunctional protein. Other mutations change single protein building blocks (amino acids) in the OCTN2 protein.

Mutations in the SLC22A5 gene result in an absent or dysfunctional OCTN2 protein. As a result, there is a shortage (deficiency) of carnitine within cells. Without carnitine, fatty acids cannot enter mitochondria and be used to make energy. Reduced energy production can lead to some features of primary carnitine deficiency, such as muscle weakness and hypoglycemia. Fatty acids may also build up in cells and damage the heart, liver, and muscles. This abnormal buildup causes the other signs and symptoms of the disorder.

Where is the SLC22A5 gene located?

Cytogenetic Location: 5q23.3

Molecular Location on chromosome 5: base pairs 132,369,704 to 132,395,614

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

The SLC22A5 gene is located on the long (q) arm of chromosome 5 at position 23.3.

The SLC22A5 gene is located on the long (q) arm of chromosome 5 at position 23.3.

More precisely, the SLC22A5 gene is located from base pair 132,369,704 to base pair 132,395,614 on chromosome 5.

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

Where can I find additional information about SLC22A5?

You and your healthcare professional may find the following resources about SLC22A5 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 SLC22A5 gene or gene products?

  • CDSP
  • high-affinity sodium dependent carnitine cotransporter
  • novel organic cation transporter 2
  • OCTN2
  • organic cation/carnitine transporter 2
  • organic cation transporter 5
  • S22A5_HUMAN
  • SCD
  • solute carrier family 22 member 5
  • solute carrier family 22 (organic cation transporter), member 5

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

What glossary definitions help with understanding SLC22A5?

acids ; carnitine ; carrier ; cation ; cell ; cell membrane ; deficiency ; fasting ; fatty acids ; gene ; hypoglycemia ; mitochondria ; oxidation ; protein ; sodium ; solute

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


  • Amat di San Filippo C, Longo N. Tyrosine residues affecting sodium stimulation of carnitine transport in the OCTN2 carnitine/organic cation transporter. J Biol Chem. 2004 Feb 20;279(8):7247-53. Epub 2003 Dec 9. (
  • Amat di San Filippo C, Wang Y, Longo N. Functional domains in the carnitine transporter OCTN2, defective in primary carnitine deficiency. J Biol Chem. 2003 Nov 28;278(48):47776-84. Epub 2003 Sep 23. (
  • Inano A, Sai Y, Kato Y, Tamai I, Ishiguro M, Tsuji A. Functional regions of organic cation/carnitine transporter OCTN2 (SLC22A5): roles in carnitine recognition. Drug Metab Pharmacokinet. 2004 Jun;19(3):180-9. (
  • Koepsell H, Endou H. The SLC22 drug transporter family. Pflugers Arch. 2004 Feb;447(5):666-76. Epub 2003 Jul 19. Review. (
  • Lahjouji K, Mitchell GA, Qureshi IA. Carnitine transport by organic cation transporters and systemic carnitine deficiency. Mol Genet Metab. 2001 Aug;73(4):287-97. Review. (
  • Li FY, El-Hattab AW, Bawle EV, Boles RG, Schmitt ES, Scaglia F, Wong LJ. Molecular spectrum of SLC22A5 (OCTN2) gene mutations detected in 143 subjects evaluated for systemic carnitine deficiency. Hum Mutat. 2010 Aug;31(8):E1632-51. doi: 10.1002/humu.21311. (
  • NCBI Gene (
  • Nezu J, Tamai I, Oku A, Ohashi R, Yabuuchi H, Hashimoto N, Nikaido H, Sai Y, Koizumi A, Shoji Y, Takada G, Matsuishi T, Yoshino M, Kato H, Ohura T, Tsujimoto G, Hayakawa J, Shimane M, Tsuji A. Primary systemic carnitine deficiency is caused by mutations in a gene encoding sodium ion-dependent carnitine transporter. Nat Genet. 1999 Jan;21(1):91-4. (
  • Tein I. Carnitine transport: pathophysiology and metabolism of known molecular defects. J Inherit Metab Dis. 2003;26(2-3):147-69. Review. (


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: July 2006
Published: February 1, 2016