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Start free with EleplanAdult Refsum disease
ORPHA:773Disease
Also called Classic Refsum disease · HMSN 4 · HMSN IV · Hereditary motor and sensory neuropathy type 4 · Hereditary motor and sensory neuropathy type IV · Heredopathia atactica polyneuritiformis · Phytanic-CoA hydroxylase deficiency
What it is
A metabolic disease characterized by anosmia, cataract, early-onset retinitis pigmentosa and possible neurological manifestations, including peripheral neuropathy and cerebellar ataxia. Other features can be deafness, ichthyosis, skeletal abnormalities, and cardiac arrhythmia. It is characterized biochemically by accumulation of phytanic acid in plasma and tissues.
Key facts
- Prevalence
- 1-9 / 1 000 000 (Europe)
- Age of onset
- Adolescent, Adult, 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
Very common80–99%
18- Abnormal foot morphology
- Abnormality of metabolism/homeostasis
- Abnormality of retinal pigmentation
- Abnormality of the eye
- Abnormality of vision
- Abnormal pyramidal sign
- Anosmia
- Ataxia
- Cardiomyopathy
- Cataract
- Dry skin
- Hemiplegia/hemiparesis
- Ichthyosis
- Nail dysplasia
- Peripheral neuropathy
- Retinopathy
- Sensorineural hearing impairment
- Skeletal dysplasia
Common30–79%
13These 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
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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