Diagnosis of Refsum's disease using [1-14C]phytanic acid as substrate

The suitability of using [1-14C]phytanic acid as a substrate for the diagnosis of Refsum's disease has been examined. Normal fibroblasts cultured in medium containing low concentrations of foetal calf serum (0.5%) oxidised added [1-14C]phytanic acid to 14CO2 only slowly up to about 2 days; beyond this period a marked stimulation in oxidation was observed. Easily measurable conversion of the radiolabelled acid (from 1.5 to 5.0%) was obtained by numbers of cells at least one order of magnitude fewer than previously described. Fibroblasts from adult patients with Refsum's disease displayed about 5-10% of the normal mean activity. Small differences in residual activity were observed in the different cell lines. However, no obvious relationship was found between the degree of residual activity, the level of plasma phytanate, and the patient's clinical condition and history.