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Start free with EleplanProximal spinal muscular atrophy type 1
ORPHA:83330Clinical subtype
Also called Infantile spinal muscular atrophy · Infantile-onset spinal muscular atrophy · SMA type 1 · SMA type I · SMA-I · SMA1 · Werdnig-Hoffmann disease
What it is
A rare genetic motor neuron disorder characterized by degeneration of alpha motor neurons in the spinal cord and lower brainstem manifesting within the first six months of life with severe and progressive muscle weakness, including respiratory insufficiency and dysphagia. Classically, before the introduction of disease-modifying therapies, patients with proximal spinal muscular atrophy (SMA) type 1 never achieved independent sitting.
Key facts
- Prevalence
- 1-9 / 100 000 (Europe)
- Age of onset
- Infancy, Neonatal
- Inheritance
- Autosomal recessive
- Classified as
- Clinical subtype
Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.
Genes
2 modifying genes — variants that can change how the disease behaves, not cause it
ICD-10 codes
ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.
Related health topics
Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.
Benefit programs to look at
Programs whose eligibility touches the same ICD-10 categories. Eligibility is decided by the administering agency, never by this page.
Cross-references
Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.
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