2,6-Dimethyloctanedioic acid--a metabolite of phytanic acid in Refsum's disease

The urine of two patients with Refsum's disease consistently contained 2,6-dimethyloctanedioic acid, a compound not normally found in human urine. In addition, their urines contained increased concentrations of 3-methylhexanedioic acid. These two compounds may be formed from phytanic acid by an initial omega-oxidation and subsequent beta-oxidations. It was calculated that this oxidation pathway may metabolize at least 30 mg of phytanic acid per day.