Proximal spinal muscular atrophy

What it is

A group of rare genetic motor neuron disorders caused by degeneration of alpha motor neurons in the spinal cord and lower brainstem. It leads to progressive muscle weakness predominantly affecting proximal lower limb muscles. Severity varies from severe infantile-onset forms to milder, slowly progressive adult-onset types.

Key facts

Prevalence

1-9 / 100 000 (annual incidence, Europe)

Age of onset

All ages

Inheritance

Autosomal recessive

Classified as

Disease

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.

Signs and symptoms

These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.

Genes reported in subtypes

Orphanet records these genes on 4 more specific entries under this disorder, not on this entry itself:

A well-studied disease is usually split into subtypes, and the gene is curated on whichever one the evidence belongs to. Open a subtype to see which gene goes with 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