Spinal muscular atrophy: genes and variants
Spinal muscular atrophy is linked to 1 analyzed protein (SMN1). 9 DNA variants are known to cause it; 8 more are uncertain, and 0 of those already look disease-causing on computable evidence.
Last updated 2026-09-30. Research information, not medical advice.
Also known as: spinal muscular atrophy, type 1; spinal muscular atrophy, type II; spinal muscular atrophy, type III; spinal muscular atrophy, type IV
Genes linked to Spinal muscular atrophy
SMN1: Survival motor neuron protein
It is required for assembly of small nuclear ribonucleoproteins and other RNA-protein complexes, with motor neurons being especially sensitive to reduced protein levels. Biallelic loss of functional SMN1 causes spinal muscular atrophy, whose severity is strongly modified by SMN2 copy number.
9 disease-causing and 8 uncertain variants in SMN1 are linked to Spinal muscular atrophy.
Where Spinal muscular atrophy variants cluster
- SMN1 Involved in homooligomerization (positions 252–280): 5 of 9 disease-causing changes, 5.6× more than its size predicts.
- SMN1 Required for interaction with SYNCRIP (positions 279–294): 4 of 9 disease-causing changes, 8.2× more than its size predicts.
Known disease-causing variants in Spinal muscular atrophy
| Variant | Position | Protein part | Clinical label |
|---|---|---|---|
| SMN1 G279D | 279 | Required for interaction with SYNCRIP | Disease-causing (★★) |
| SMN1 G279V | 279 | Required for interaction with SYNCRIP | Disease-causing (★★) |
| SMN1 G279C | 279 | Required for interaction with SYNCRIP | Disease-causing (★★) |
| SMN1 G279R | 279 | Required for interaction with SYNCRIP | Disease-causing (★★) |
| SMN1 Y272C | 272 | Involved in homooligomerization | Disease-causing (★★) |
| SMN1 G95R | 95 | Tudor | Disease-causing (★★) |
| SMN1 A2G | 2 | Disease-causing (★★) | |
| SMN1 I116T | 116 | Tudor | Disease-causing (★★) |
| SMN1 D30N | 30 | Interacts with GEMIN2 | Disease-causing |
Same protein, different disease
- Kugelberg-Welander disease is also caused by SMN1 variants; they fall mostly in different places as the Spinal muscular atrophy variants (10 disease-causing).
- Werdnig-Hoffmann disease is also caused by SMN1 variants; they fall partly in the same places as the Spinal muscular atrophy variants (6 disease-causing).
Diseases related to Spinal muscular atrophy
- Kugelberg-Welander disease, also linked to SMN1
- Werdnig-Hoffmann disease, also linked to SMN1
Frequently asked questions
Which genes are linked to Spinal muscular atrophy?
In CATVariant, Spinal muscular atrophy is linked to 1 analyzed protein: SMN1 (Survival motor neuron protein).
How many genetic variants are linked to Spinal muscular atrophy?
43 variants: 9 are classified as disease-causing (pathogenic or likely pathogenic) in ClinVar and 8 are of uncertain significance or have conflicting reports.
Which uncertain variants in Spinal muscular atrophy look disease-causing?
None of the uncertain variants currently reaches the likely-pathogenic range on computable evidence alone.
About this data
Variant–disease links come from ClinVar, Open Targets and UniProt, pooled from the latest public CATVariant analysis of each human protein. Evidence scores use the ACMG/AMP Bayesian points scale with computable criteria only (position among known disease variants, rarity in gnomAD, calibrated predictors, deep mutational scanning); there is no family or patient data, so they prioritise variants for expert review and never classify them.
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