Catastrophic visual loss in a patient with Friedreich ataxia.

Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative disorder usually characterized by progressive early-onset ataxia. The most common ophthalmic manifestation of FRDA is optic neuropathy, which is usually late in onset, is slowly progressive, and rarely causes severe visual loss. The genetic basis of FRDA in most patients is the homozygous expansion of a GAA trinucleotide repeat within the first intron of the FRDA gene, which encodes the mitochondrial protein frataxin. Mutations in frataxin cause progressive iron accumulation in mitochondria. Four percent of patients are compound heterozygotes for the GAA expansion on one allele and a point mutation on the other. We describe a patient with FRDA who was a compound heterozygote for the GAA expansion and a Gly130Val missense mutation, developed rapid-onset catastrophic visual loss, and was found to have clinical, electrophysiological, and radiological evidence of a severe optic neuropathy. In addition, she had pattern dystrophy. To our knowledge, this is the first description of a patient with FRDA with this phenotype.