spinal muscular atrophy, type IV
Findings
No curated finding names spinal muscular atrophy, type IV yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
Proximal spinal muscular atrophy type 4 (SMA4) is the adult-onset form of proximal spinal muscular atrophy characterized by muscle weakness and hypotonia resulting from the degeneration and loss of the lower motor neurons in the spinal cord and the brain stem nuclei.
Definition from the Mondo Disease Ontology (MONDO:0010056), read 2026-09-29. CC BY 4.0.
- Inheritance
- Autosomal recessive inheritance
- Onset and course
- Slowly progressive · Young adult onset
HPO, annotations 2026-09-02
Features
13 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Angulated muscle fibersHPOHP:0034045
- 1 of 1 reported patient
- Centrally nucleated skeletal muscle fibersHPOHP:0003687
- 1 of 1 reported patient
- Increased variability in muscle fiber diameterHPOHP:0003557
- 1 of 1 reported patient
- Muscle fiber necrosisHPOHP:0003713
- 1 of 1 reported patient
- Proximal muscle weaknessHPOHP:0003701
- 6 of 6 reported patients
- Rimmed vacuolesHPOHP:0003805
- 1 of 1 reported patient
- Type 1 muscle fiber predominanceHPO
Show the remaining 1
- Spinal muscular atrophyHPOHP:0007269
Genes
1 gene
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- SMN1; SMN2HGNC:11117
- Strong · Genomics England PanelApp · Autosomal recessive · 2021
- Strong · Labcorp Genetics (formerly Invitae) · Autosomal recessive · 2020
- Supportive · Orphanet · Autosomal recessive · 2021
Where it sits
- A kind of
Other names
7 names
Resolves to: spinal muscular atrophy, type IV
- Also called
- SMA type 4SMA type IVSMA-IVSMA4spinal muscular atrophy of adultsspinal muscular atrophy-4spinal muscular atrophy, adult form