An adult onset case of alpha-methyl-acyl-CoA racemase deficiency

α-Methyl-acyl-CoA-racemase (AMACR) deficiency (OMIM 604489) is a rare peroxisomal disorder with a variable age of onset from infancy to late adulthood. We describe a 45-year-old male with a history of seizures who presented with relapsing encephalopathy. Laboratory studies revealed an elevated serum pristanic acid concentration, an elevated pristanic/phytanic acid ratio, as well as the previously described homozygous mutation in the AMACR gene, c.154T>C, consistent with AMACR deficiency. This homozygous mutation is associated with a variable phenotype ranging from neonatal cholestasis to late-onset sensorimotor neuropathy. Dietary pristanic acid restriction was attempted to improve clinical status and the patient has remained in remission for more than 16 months.