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.

Orphanet doesn't provide personalised answers. To get in touch with the Orphanet team, please contact

Information provided in your contribution (including your email address) will be stocked in .CSV files that will be sent as an email to Orphanet's teams. These emails might be conserved in the teams' mailboxes, in our backoffice servers but will not be registered in our databases (for more information see our section General Data Protection Regulation and data privacy (GDPR) and Confidentiality).

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):
    • 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.