pediatrics
Peroxisomal Disorders
Classic Refsum disease
Genetic deficiency of a single peroxisomal enzyme, phytanoyl-CoA hydroxylase, which catalyzes metabolism of phytanic acid (a common dietary plant component), causes phytanic acid accumulation. Clinical manifestations include progressive peripheral neuropathy, impaired vision caused by Retinitis Pigmentosa , hearing deficit, anosmia, cardiomyopathy and conduction defects, and ichthyosis. Onset is usually in the 20s. Diagnosis of Refsum disease is confirmed by elevation of serum phytanic acid and decreased levels of pristanic acid (phytanic acid elevation is accompanied by pristanic acid elevation in several other peroxisomal disorders). Treatment of Refsum disease is dietary restriction of phytanic acid (<10 mg/day), which can be effective in preventing or delaying symptoms when started before symptom onset. 