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Information for clinicians

2 Diagnosis

2a Clinical diagnosis

Adult Refsum's disease (ARD) is suspected in individuals with late childhood-onset retinitis pigmentosa and variable combinations (in decreasing order of frequency) of the following manifestations:

Note: The full constellation of signs is rarely seen in an individual. Neuropathy and ataxia are present in about 50% of individuals, but usually manifest after childhood.

 

Figure 2.1 Cumulative incidence of clinical features on presentation of 15 patients with adult Refsum's disease. (RP= retinitis pigmentosa.)

'Number of patients' - label for vertical access of Figure 1Figure 1: Graph showing the cumulative incidence of clinical features on presentation of 15 patients with adult Refsum's disease

2b Differential Diagnosis

2b(i) a-Methylacyl-CoA racemase (AMACR) deficiency (OMIM 604489)

This enzyme deficiency leads to an ARD-like condition but is accompanied by high plasma concentrations of pristanic acid and the C27-bile-acid intermediates, whereas the plasma phytanic acid concentration is low. The phenotype is one of adult-onset sensory motor neuropathy with or without associated pigmentary retinopathy [Ferdinandusse et al 2000].

2b(ii) Retinitis pigmentosa

Since visual deterioration is almost always the first symptom of adult Refsum's disease, plasma phytanic acid concentration should be measured in any individual with retinitis pigmentosa, especially when combined with other features, including anosmia and impaired hearing. (See also the GeneReview: Retinitis Pigmentosa Overview.)

2b(iii) Retinitis pigmentosa and sensorineural hearing loss

2b(iv) Ataxia

Friedreich ataxia is characterized by slowly progressive ataxia with onset usually before the age of 25 years typically associated with depressed tendon reflexes, dysarthria, Babinski responses, and loss of position and vibration senses. Hearing loss is uncommon. Inheritance is autosomal recessive. (See also the GeneReview: Ataxia Overview.)

2b(v) Ichthyosis

Sjögren-Larsson syndrome is characterized by congenital ichthyosis and onset of ataxia in early childhood.

2b(vi) Increased CSF protein concentration

High CSF protein concentrations can be found in a variety of conditions.

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Page last updated 26 June 2006