Increased serum transferrin receptor concentrations in Friedreich ataxia.

Mitochondrial iron accumulation is thought to underlie the pathophysiology of Friedreich ataxia and may occur at the expense of cytosolic iron. Decreases in cytosolic iron induce expression of the transferrin receptor, some of which is released into the serum. Here, we demonstrate that serum transferrin receptor concentrations are increased in patients with Friedreich ataxia, which supports the hypothesis that it is a disease of abnormal intracellular iron distribution.