[Refsum disease].

Refsum's disease, firstly described almost 50 years ago by the Norvegian neurologist Sigvald Refsum, is an autosomic recessive disease affecting mostly the Scandinavians and the populations originating from Northern Europe. The disease results from a specific enzyme deficiency of the first step of phytanic acid catabolism pathway. This deficiency leads to an accumulation of this C20 fatty acid in the serum and the tissues with a preference for adipose tissue, liver and kidneys. The clinical picture includes retinitis pigmentosa, peripheral neuropathy, ataxia and elevated cerebrospinal fluid protein concentration. Other less frequent manifestations include cranial nerves deficiency, myocardiopathy, renal tubular dysfunction and ichtyosis. The diagnosis relies on serum phytanic acid measurement. The treatment consists of a phytanic-acid free diet sometimes associated with plasmapheresis. This treatment is generally effective on neuropathy but not on cranial nerves dysfunction and retinitis pigmentosa.