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SMS gene

spermine synthase

Normal Function

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.

Health Conditions Related to Genetic Changes

Snyder-Robinson syndrome

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.

More About This Health Condition

Other Names for This Gene

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

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Catalog of Genes and Diseases from OMIM

Gene and Variant Databases


  • Becerra-Solano LE, Butler J, Castaneda-Cisneros G, McCloskey DE, Wang X, Pegg AE, Schwartz CE, Sanchez-Corona J, Garcia-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. Citation on PubMed or Free article on PubMed Central
  • 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. doi: 10.1038/sj.ejhg.5201072. Citation on PubMed
  • de Alencastro G, McCloskey DE, Kliemann SE, Maranduba CM, Pegg AE, Wang X, Bertola DR, Schwartz CE, Passos-Bueno MR, Sertie 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. Citation on PubMed
  • 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. Citation on PubMed or Free article on PubMed Central
  • 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. Citation on PubMed
  • 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. Citation on PubMed or Free article on PubMed Central
  • 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. Citation on PubMed or Free article on PubMed Central

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.