Kugelberg-Welander disease: genes and variants
Kugelberg-Welander disease is linked to 1 analyzed protein (SMN1). 10 DNA variants are known to cause it; 3 more are uncertain, and 0 of those already look disease-causing on computable evidence.
Last updated 2026-09-30. Research information, not medical advice.
Genes linked to Kugelberg-Welander disease
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.
10 disease-causing and 3 uncertain variants in SMN1 are linked to Kugelberg-Welander disease.
Where Kugelberg-Welander disease variants cluster
- SMN1 Involved in homooligomerization (positions 252–280): 4 of 10 disease-causing changes, 4.1× more than its size predicts.
- SMN1 P2 (binding site for SNRPB) (positions 240–267): 3 of 10 disease-causing changes, 3.1× more than its size predicts.
- SMN1 Tudor (positions 91–151): 4 of 10 disease-causing changes, 1.9× more than its size predicts.
Known disease-causing variants in Kugelberg-Welander disease
| Variant | Position | Protein part | Clinical label |
|---|---|---|---|
| SMN1 S262I | 262 | P2 (binding site for SNRPB) | Disease-causing (★★) |
| SMN1 A2G | 2 | Disease-causing (★★) | |
| SMN1 I116T | 116 | Tudor | Disease-causing (★★) |
| SMN1 D256Y | 256 | P2 (binding site for SNRPB) | Disease-causing (★) |
| SMN1 S270G | 270 | Involved in homooligomerization | Disease-causing (★) |
| SMN1 Y130H | 130 | Tudor | Disease-causing |
| SMN1 Y130C | 130 | Tudor | Disease-causing |
| SMN1 Y127H | 127 | Tudor | Disease-causing |
| SMN1 S262G | 262 | P2 (binding site for SNRPB) | Disease-causing |
| SMN1 D44V | 44 | Interacts with GEMIN2 | Disease-causing |
Same protein, different disease
- Spinal muscular atrophy is also caused by SMN1 variants; they fall mostly in different places as the Kugelberg-Welander disease variants (9 disease-causing).
- Werdnig-Hoffmann disease is also caused by SMN1 variants; they fall mostly in different places as the Kugelberg-Welander disease variants (6 disease-causing).
Diseases related to Kugelberg-Welander disease
- Spinal muscular atrophy, also linked to SMN1
- Werdnig-Hoffmann disease, also linked to SMN1
Frequently asked questions
Which genes are linked to Kugelberg-Welander disease?
In CATVariant, Kugelberg-Welander disease is linked to 1 analyzed protein: SMN1 (Survival motor neuron protein).
How many genetic variants are linked to Kugelberg-Welander disease?
13 variants: 10 are classified as disease-causing (pathogenic or likely pathogenic) in ClinVar and 3 are of uncertain significance or have conflicting reports.
Which uncertain variants in Kugelberg-Welander disease 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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