Orphanet: Search a disease

Search for a rare disease

* (*) mandatory field

Other search option(s)

Suggest an update

(*) Required fields.


Only comments seeking to improve the quality and accuracy of information on the Orphanet website are accepted. For all other comments, please send your remarks via contact us. Only comments written in English can be processed.

Captcha image

Proximal spinal muscular atrophy type 2

Disease definition

A rare, genetic proximal spinal muscular atrophy characterized by degeneration of alpha motor neurons in the anterior horns of the spinal cord and lower brain stem manifesting with onset between 6 to 18 months of age with progressive, proximal muscle weakness, mild to moderate hypotonia and finger polymyoclonour tremor, with areflexia. Motor milestones are classically limited to independent sitting or standing.


Classification level: Subtype of disorder
  • Synonym(s):
    • Chronic infantile spinal muscular atrophy
    • Chronic spinal muscular atrophy
    • Intermediate spinal muscular atrophy
    • SMA type 2
    • SMA type II
    • SMA-II
    • SMA2
  • Prevalence: 1-9 / 100 000
  • Inheritance: Autosomal recessive 
  • Age of onset: Infancy, Neonatal
  • ICD-10: G12.1
  • OMIM: 253550
  • UMLS: C0393538  C2931358
  • MeSH: -
  • GARD: 4945
  • MedDRA: -

Detailed information

Article for general public


The documents contained in this web site are presented for information purposes only. The material is in no way intended to replace professional medical care by a qualified specialist and should not be used as a basis for diagnosis or treatment.