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SMS gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

SMS gene

The SMS gene provides instructions for producing an enzyme critical for the creation of polyamines, which are essential for cell growth, division, and development.

Normal Function

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

Polyamines have many critical functions within cells, including:

  • Cell growth and division
  • Production of new proteins
  • Repair of damaged tissues
  • Controlled self-destruction of cells (apoptosis)
  • 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 that occurs only in males. Most identified mutations change a single amino acid in the spermine synthase enzyme, greatly reducing or eliminating its activity and decreasing the amount of spermine in cells. While a shortage of this polyamine clearly impacts the development of the brain, muscles, and bones, it is currently unknown how it leads to the specific signs and symptoms of the syndrome.

Other Names for This Gene

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

Frequently Asked Questions

Snyder-Robinson syndrome typically presents in infancy or early childhood. Key early signs include severe intellectual disability, significant developmental delays (e.g., delayed walking and speech), muscle weakness (hypotonia), and distinctive facial features. Bone abnormalities, such as osteoporosis and scoliosis, may also develop over time.
While spermine is crucial for cell function, the exact mechanism by which its shortage causes Snyder-Robinson syndrome is still being researched. There are currently no established dietary or supplement interventions proven to effectively treat the condition. Any potential interventions would need to be carefully studied and administered under medical supervision due to the complex roles of polyamines in the body.
Snyder-Robinson syndrome is an X-linked recessive condition, meaning it primarily affects males. Females can be carriers without showing symptoms. If a mother is a carrier, there is a 50% chance that each son will inherit the condition and a 50% chance that each daughter will be a carrier. Genetic counseling can help families understand their specific risks.
Currently, there is no cure for Snyder-Robinson syndrome, and treatment is primarily supportive, focusing on managing symptoms and improving quality of life. This often involves physical therapy for muscle weakness, occupational therapy for daily living skills, speech therapy for communication, and educational support for intellectual disability. Medications may be used to manage specific symptoms like seizures or bone issues.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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