Refsum disease is a rare inherited metabolic disorder arising from a defect in peroxisomal metabolism. Patients lack the functional
enzyme phytanoyl-CoA hydroxylase, resulting in perturbed alpha oxidation of
fatty acids.
Phytanic acid accumulates in nervous and adipose tissue and leads to several disease phenotypes including early-onset
retinal degeneration,
hearing loss,
peripheral neuropathy,
anosmia, and
cerebellar ataxia, among others. Currently, restricting dietary
phytanic acid is the only means of altering the chronic sequelae and the disease course. While dietary intervention has been demonstrated to improve
peripheral neuropathy,
ichthyosis, and
ataxia, there have been no reports of improved
retinal function in patients with
Refsum disease. We describe the case of a 51-year-old patient with molecularly and biochemically confirmed
Refsum disease who underwent electroretinography before and after beginning a
phytanic acid-restricted diet. His post-intervention 30 Hz flicker electroretinogram demonstrated significantly improved waveform amplitudes and implicit times, suggesting improved
retinal function. Thus, we propose that the possibility exists for some visual recovery in these patients and we highlight the utility of performing standardized electroretinography to assess treatment response in
Refsum disease.