(Sigvald Refsum, born 1907, Norwegian neurologist), deficiency of the enzyme phytanic acid hydroxylase which results in accumulation of phytanic acid in liver, kidney, heart and peripheral nerves. Inheritance is autosomal recessive. The clinical manifestations are visual deterioration, ichtyosis and renal impairment. Radiologically there is osteopenia in the infantile form, and mild epiphyseal dysplasia with irregular flattening of the epiphysis.