Influence of plasma phytanic acid levels in Refsum's disease on the behaviour of the erythrocyte membrane sodium-lithium countertransporter

Background Abnormal behaviour of the erythrocyte membrane sodium–lithium countertransporter (SLC) is associated with plasma triglyceride concentrations. Refsum's disease is characterized by progressive neurological dysfunction and accumulation of phytanic acid, an isoprenoid fatty acid, in fat‐containing tissues. Methods This study explored the effects of plasma phytanic acid on SLC kinetics in nine Caucasian patients with Refsum's disease and in age‐ and sex‐matched Caucasian control subjects. Results A dose‐dependent association was seen between countertransporter maximal velocity and phytanic acid content of low‐density lipoprotein (LDL)‐cholesterol (r = −0.61, r = −0.65 respectively; P = 0.05, P = 0.04) and high‐density lipoprotein (HDL)‐cholesterol (r = − 0.81, − 0.82 respectively; P = 0.005, P = 0.003). No significant association was seen with the sodium affinity of the transporter (r = − 0.44, P = 0.20, for LDL; and − 0.43, P = 0.21, for high‐density lipoprotein). Conclusion These findings suggest that phytanic acid may alter the behaviour of the sodium–lithium countertransporter.