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Start free with EleplanAutosomal recessive spastic paraplegia type 55
ORPHA:320375Disease
Also called SPG55
What it is
Autosomal recessive spastic paraplegia type 55 (SPG 55) is a rare, complex type of hereditary spastic paraplegia characterized by childhood onset of progressive spastic paraplegia associated with optic atrophy (with reduced visual acuity and central scotoma), ophthalmoplegia, reduced upper-extremity strength and dexterity, muscular atrophy in the lower extremities, and sensorimotor neuropathy. SPG55 is caused by mutations in the C12ORF65 gene (12q24.31) encoding probable peptide chain release factor C12orf65, mitochondrial.
Key facts
- Prevalence
- <1 / 1 000 000
- Age of onset
- Childhood
- 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
Common30–79%
22- Babinski sign
- Decreased sensory nerve conduction velocity
- Distal sensory impairment
- Focal white matter lesions
- Foot dorsiflexor weakness
- Hyperreflexia
- Hypoplasia of the corpus callosum
- Intellectual disability, mild
- Lower limb muscle weakness
- Lower limb spasticity
- Onion bulb formation
- Optic atrophy
- Optic neuropathy
- Peripheral neuropathy
- Poor fine motor coordination
- Reduced visual acuity
- Skeletal muscle atrophy
- Spasticity
- Spastic paraparesis
- Talipes equinovarus
- Tibialis muscle weakness
- Upper limb muscle weakness
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.
Gene
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.
Cross-references
Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.
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