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Lower motor neuron syndrome with late-adult onset

Disease definition

A rare, genetic, motor neuron disease characterized by slowly progressive, predominantly proximal, muscular weakness and atrophy which typically manifests with muscle cramps, fasciculations, decreased/absent deep tendon reflexes, hand tremor, and elevated serum creatine kinase at onset and later associates with reduced walking ability and impaired vibration sensation.


Classification level: Disorder
  • Synonym(s):
    • LOSMoN
    • Late-onset spinal motor neuronopathy
    • SMAJ
    • Spinal muscular atrophy, Jokela type
  • Prevalence: <1 / 1 000 000
  • Inheritance: Autosomal dominant 
  • Age of onset: Adult
  • ICD-10: G12.1
  • ICD-11: 8B60.Y
  • OMIM: 615048
  • UMLS: C5191007
  • MeSH: -
  • GARD: -
  • MedDRA: -

Detailed information

Disease review articles

Clinical Outcome Assessment (COA)

  • Patient-Centered Outcome Measures (PCOMs)
  • English (2023) - PROQOLIDTM

Genetic Testing

ERN produced/endorsed by ERN(s)   FSMR produced/endorsed by FSMR(s)
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