Multisystemic smooth muscle dysfunction syndrome: genes and variants
Multisystemic smooth muscle dysfunction syndrome is linked to 1 analyzed protein (ACTA2). 6 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.
Genes linked to Multisystemic smooth muscle dysfunction syndrome
ACTA2: Actin, aortic smooth muscle
Its smooth-muscle actin filaments generate contractile force in arteries and visceral organs and help maintain vascular-wall structure. Pathogenic variants are an important cause of familial thoracic aortic aneurysm and dissection and can also produce occlusive vascular disease.
6 disease-causing and 8 uncertain variants in ACTA2 are linked to Multisystemic smooth muscle dysfunction syndrome.
Known disease-causing variants in Multisystemic smooth muscle dysfunction syndrome
| Variant | Position | Protein part | Clinical label |
|---|---|---|---|
| ACTA2 R179S | 179 | Disease-causing (★★) | |
| ACTA2 R179H | 179 | Disease-causing (★★) | |
| ACTA2 R179L | 179 | Disease-causing (★★) | |
| ACTA2 R118Q | 118 | Disease-causing (★★) | |
| ACTA2 R39C | 39 | Disease-causing (★★) | |
| ACTA2 R198H | 198 | Disease-causing |
Same protein, different disease
- Aortic aneurysm, familial thoracic 7 is also caused by ACTA2 variants; they fall mostly in different places as the Multisystemic smooth muscle dysfunction syndrome variants (20 disease-causing).
- Familial thoracic aortic aneurysm and aortic dissection is also caused by ACTA2 variants; they fall partly in the same places as the Multisystemic smooth muscle dysfunction syndrome variants (8 disease-causing).
- Familial aortopathy is also caused by ACTA2 variants; they fall partly in the same places as the Multisystemic smooth muscle dysfunction syndrome variants (5 disease-causing).
Diseases related to Multisystemic smooth muscle dysfunction syndrome
- Familial thoracic aortic aneurysm and aortic dissection, also linked to ACTA2
- Aortic aneurysm, familial thoracic 7, also linked to ACTA2
- Familial aortopathy, also linked to ACTA2
- Isolated thoracic aortic aneurysm, also linked to ACTA2
- Thoracic aortic aneurysm or dissection, also linked to ACTA2
- Moyamoya disease, also linked to ACTA2
Frequently asked questions
Which genes are linked to Multisystemic smooth muscle dysfunction syndrome?
In CATVariant, Multisystemic smooth muscle dysfunction syndrome is linked to 1 analyzed protein: ACTA2 (Actin, aortic smooth muscle).
How many genetic variants are linked to Multisystemic smooth muscle dysfunction syndrome?
16 variants: 6 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 Multisystemic smooth muscle dysfunction syndrome 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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