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Start free with EleplanLeukoencephalopathy-spondyloepimetaphyseal dysplasia syndrome
ORPHA:83629Disease
Also called H-SMD · Hypomyelination-spondyloepimetaphyseal dysplasia syndrome · Leukoencephalopathy-SEMD syndrome · Leukoencephalopathy-metaphyseal chondrodysplasia syndrome
What it is
A rare genetic neurological disorder characterized by the association of hypomyelinating leukodystrophy with spondylometaphyseal dysplasia. Patients present in infancy with absent or delayed ability to walk independently, slowly progressive motor deterioration, spasticity, ataxia, proximal weakness, and joint contractures. Additional manifestations include mild cognitive impairment, short stature, scoliosis, enlarged and deformed joints, dysarthria, nystagmus, visual defects, and mildly dysmorphic features, among others. Mode of inheritance is X-linked recessive.
Key facts
- Prevalence
- <1 / 1 000 000
- Age of onset
- Childhood, Infancy
- Inheritance
- X-linked 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%
17- Abnormal astrocyte morphology
- Abnormal brainstem MRI signal intensity
- Abnormal optic nerve morphology
- Babinski sign
- Cerebral atrophy
- Enlargement of the wrists
- Gait disturbance
- Hyperreflexia
- Hypoplasia of the corpus callosum
- Intellectual disability
- Large knee
- Morphological abnormality of the pyramidal tract
- Reduced bone mineral density
- Spastic paraplegia
- Tip-toe gait
- Tremor
- Visual impairment
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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