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


Reviewed August 2013

What is the official name of the SMS gene?

The official name of this gene is “spermine synthase.”

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

What is the normal function of the SMS gene?

The SMS gene provides instructions for making an enzyme called spermine synthase. This enzyme is involved in the production of spermine, which is a type of small molecule called a polyamine. Specifically, the enzyme carries out the reaction that creates spermine from a related polyamine, spermidine.

Polyamines have many critical functions within cells. Studies suggest that these molecules play roles in cell growth and division, the production of new proteins, the repair of damaged tissues, and the controlled self-destruction of cells (apoptosis). Polyamines also appear to be necessary for normal development of the brain and other parts of the body.

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

Snyder-Robinson syndrome - caused by mutations in the SMS gene

At least four mutations in the SMS gene have been found to cause Snyder-Robinson syndrome, a condition characterized by intellectual disability and bone and muscle abnormalities. The condition only occurs in males. Most of the identified mutations change a single protein building block (amino acid) in the spermine synthase enzyme. All of the known mutations greatly reduce or eliminate the activity of spermine synthase, which decreases the amount of spermine in cells. A shortage of this polyamine clearly impacts normal development, including the development of the brain, muscles, and bones, but it is unknown how it leads to the specific signs and symptoms of Snyder-Robinson syndrome.

Where is the SMS gene located?

Cytogenetic Location: Xp22.1

Molecular Location on the X chromosome: base pairs 21,940,573 to 21,994,837

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

The SMS gene is located on the short (p) arm of the X chromosome at position 22.1.

The SMS gene is located on the short (p) arm of the X chromosome at position 22.1.

More precisely, the SMS gene is located from base pair 21,940,573 to base pair 21,994,837 on the X chromosome.

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

Where can I find additional information about SMS?

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

  • spermidine aminopropyltransferase
  • spermine synthase isoform 1
  • spermine synthase isoform 2
  • SpS
  • SRS

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

What glossary definitions help with understanding SMS?

amino acid ; apoptosis ; cell ; disability ; enzyme ; gene ; molecule ; polyamine ; protein ; syndrome

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


  • Becerra-Solano LE, Butler J, Castañeda-Cisneros G, McCloskey DE, Wang X, Pegg AE, Schwartz CE, Sánchez-Corona J, García-Ortiz JE. A missense mutation, p.V132G, in the X-linked spermine synthase gene (SMS) causes Snyder-Robinson syndrome. Am J Med Genet A. 2009 Mar;149A(3):328-35. doi: 10.1002/ajmg.a.32641. (
  • Cason AL, Ikeguchi Y, Skinner C, Wood TC, Holden KR, Lubs HA, Martinez F, Simensen RJ, Stevenson RE, Pegg AE, Schwartz CE. X-linked spermine synthase gene (SMS) defect: the first polyamine deficiency syndrome. Eur J Hum Genet. 2003 Dec;11(12):937-44. (
  • de Alencastro G, McCloskey DE, Kliemann SE, Maranduba CM, Pegg AE, Wang X, Bertola DR, Schwartz CE, Passos-Bueno MR, Sertié AL. New SMS mutation leads to a striking reduction in spermine synthase protein function and a severe form of Snyder-Robinson X-linked recessive mental retardation syndrome. J Med Genet. 2008 Aug;45(8):539-43. doi: 10.1136/jmg.2007.056713. Epub 2008 Jun 11. (
  • NCBI Gene (
  • Pegg AE, Michael AJ. Spermine synthase. Cell Mol Life Sci. 2010 Jan;67(1):113-21. doi: 10.1007/s00018-009-0165-5. Epub 2009 Oct 27. Review. (
  • Schwartz CE, Wang X, Stevenson RE, Pegg AE. Spermine synthase deficiency resulting in X-linked intellectual disability (Snyder-Robinson syndrome). Methods Mol Biol. 2011;720:437-45. doi: 10.1007/978-1-61779-034-8_28. (
  • Zhang Z, Norris J, Kalscheuer V, Wood T, Wang L, Schwartz C, Alexov E, Van Esch H. A Y328C missense mutation in spermine synthase causes a mild form of Snyder-Robinson syndrome. Hum Mol Genet. 2013 Sep 15;22(18):3789-97. doi: 10.1093/hmg/ddt229. Epub 2013 May 21. (
  • Zhang Z, Teng S, Wang L, Schwartz CE, Alexov E. Computational analysis of missense mutations causing Snyder-Robinson syndrome. Hum Mutat. 2010 Sep;31(9):1043-9. doi: 10.1002/humu.21310. (


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: August 2013
Published: February 1, 2016