SMS Gene (Spermine Synthase): Function, Expression, and Disease Associations
A comprehensive biomedical overview of the SMS gene, its protein product, genomic context, expression patterns, and clinical significance.
Gene Information Card
| Symbol | SMS |
|---|---|
| Full Name | spermine synthase |
| Gene Type | protein-coding |
| Chromosomal Location | Xp22.11 |
| NCBI Gene ID | 6611 ncbi.nlm.nih.gov/gene/6611 |
| Ensembl ID | ENSG00000102172 |
| UniProt ID | P52788 |
| OMIM ID | 300105 |
| HGNC ID | 11123 |
| Aliases | SPMSY, MRSR, SRS |
Description
The SMS gene (spermine synthase) encodes an enzyme that catalyzes the conversion of spermidine to spermine, a critical step in polyamine biosynthesis. Polyamines are essential for cell growth, differentiation, and apoptosis. Mutations in SMS are associated with Snyder-Robinson syndrome, an X-linked condition characterized by intellectual disability, hypotonia, and skeletal abnormalities.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Disease | Mechanism | Evidence |
| Snyder-Robinson syndrome (SRS) | Loss-of-function mutations in SMS lead to reduced spermine synthase activity, causing an imbalance in polyamine levels (decreased spermine, increased spermidine), which disrupts neuronal development and function. | ClinVar, OMIM (300105), multiple case reports |
| X-linked intellectual disability | SMS mutations impair polyamine homeostasis, affecting neuronal signaling and synaptic plasticity, contributing to cognitive deficits. | OMIM, literature (e.g., Cason et al., 2003) |
| Osteoporosis (potential) | Altered polyamine metabolism may affect bone formation and resorption, but evidence is preliminary. | Limited studies; not yet clinically confirmed |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Tissue | nTPM | Level |
| Testis | 34.2 | Medium |
| Brain (cerebral cortex) | 18.7 | Low |
| Liver | 12.3 | Low |
| Kidney | 10.1 | Low |
| Heart | 8.5 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| Cell Line | nTPM | Notes |
| HeLa (cervical cancer) | 15.2 | Moderate expression |
| HepG2 (liver cancer) | 12.8 | Low expression |
| A549 (lung cancer) | 9.6 | Low expression |
| SH-SY5Y (neuroblastoma) | 22.4 | Higher expression in neuronal cells |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| Variant | Type | Frequency | Effect |
| c.245G>A (p.Gly82Asp) | Missense | Rare (found in SRS families) | Loss of function; reduced enzyme activity |
| c.569G>A (p.Arg190His) | Missense | Rare (SRS) | Loss of function; impaired protein stability |
| c.682C>T (p.Arg228Ter) | Nonsense | Rare (SRS) | Truncated protein; complete loss of function |
| c.1042A>G (p.Thr348Ala) | Missense | Rare (SRS) | Loss of function; reduced catalytic activity |
Mutation functional classification
Loss of Function (LOF)
Most SMS mutations are loss-of-function, leading to reduced or absent spermine synthase activity, causing polyamine imbalance and Snyder-Robinson syndrome.
Gain of Function (GOF)
No gain-of-function mutations have been reported for SMS.
Dominant Negative (DN)
No dominant-negative effects are documented; SMS is X-linked and mutations typically act in a recessive manner in males (hemizygous).
View complete mutation data：
Gene Ontology (GO)
Pathways
• Polyamine biosynthesis (Reactome: R-HSA-351143)
• Metabolism of polyamines (KEGG: map00330)
Protein Summary
Spermine synthase is a 366-amino acid protein that belongs to the spermidine/spermine synthase family. It forms a homodimer and requires S-adenosylmethionine as a cofactor. The enzyme catalyzes the transfer of an aminopropyl group from decarboxylated S-adenosylmethionine to spermidine, producing spermine. Defects in this enzyme lead to accumulation of spermidine and depletion of spermine, affecting cellular functions, particularly in neurons and bone development.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SMS Knockout HEK293 Cell Line | EDJ-KQ50641 | Human | 6611 | Details Get a Quote |
| SMS Knockout HeLa Cell Line | EDJ-KQ54529 | Human | 6611 | Details Get a Quote |
| SMS Knockout A-549 Cell Line | EDJ-KQ63012 | Human | 6611 | Details Get a Quote |
| SMS Knockout HCT 116 Cell Line | EDJ-KQ71487 | Human | 6611 | Details Get a Quote |
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