SMS gene

spermine synthase

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.

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.

Cytogenetic Location: Xp22.1, which is the short (p) arm of the X chromosome at position 22.1

Molecular Location: base pairs 21,940,573 to 21,994,837 on the X chromosome (Homo sapiens Annotation Release 108, GRCh38.p7) (NCBI)

Cytogenetic Location: Xp22.1, which is the short (p) arm of the X chromosome at position 22.1
  • spermidine aminopropyltransferase
  • spermine synthase isoform 1
  • spermine synthase isoform 2
  • SpS
  • SRS