Refsum disease, also known as “heredopathia atactica polyneuritiformis” is a rare neurological disease characterized biochemically by accumulation of phytanic acid in blood plasma and tissues, including fat and neurons.
- Autosomal recessive inheritance
Etiopathogenesis
Adult Refsum disease 1
- Mutations in the phytanoyl-CoA hydroxylase (PAHX aka PHYH) gene, on the PHYH locus at 10p13 on chromosome 6q22-24
Adult Refsum disease 2
- Mutations in the peroxin 7 (PEX7) gene on chromosome 6q22-24
Disorder of α-oxidation
↓
Phytanic acid not metabolized to pristanic acid
↓
Phytanic acid accumulation
Presentation
Childhood/adolescence-onset with a progressive course, with periods of stagnation/remission
- Ophthalmic involvement:
- Atypical retinitis pigmentosa (earliest sign)
- Cataracts
- Night blindness
- Otologic involvement:
- Severe sensorineural deafness (80% cases)
- Neurologic damage:
- Mental and growth retardation
- Ichthyosis (scaly skin)
- Peripheral neuropathy
- Anosmia
- Cerebellar ataxia (late onset)
- Facial dysmorphism
- Hepatomegaly
- Shortening of 4th toe
Diagnosis
CSF analysis:
- ↑ CSF proteins
Skin biopsy:
Presence of cells in the basal and suprabasal layers of the epidermis containing variably sized vacuoles with accumulated lipids (PATHOGNOMIC)
- Hyperkeratosis
- Hypergranulosis
- Acanthosis
Differential diagnosis:
- Usher syndromes (types 1, 2, and 3)
- Alström syndrome
- Kearns-Sayre syndrome
- Sjögren-Larsson syndrome
Management
Lifestyle changes
- Phytanic acid-restricted diet
- Avoid the consumption of fats from ruminant animals and certain fish, such as tuna, cod, and haddoc
Medical management
- Plasmapheresis
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