Gyrate atrophy of choroid and retina

Gyrate atrophy of the choroid and retina (also known as ornithine aminotransferase deficiency or hyperornithinemia with gyrate atrophy) is a rare inherited metabolic disorder caused by deficiency of the mitochondrial enzyme ornithine aminotransferase (OAT). This enzyme deficiency leads to a marked elevation of ornithine levels in blood, urine, cerebrospinal fluid, and aqueous humor. The condition primarily affects the eyes, causing progressive chorioretinal degeneration that begins in the peripheral retina and gradually advances toward the macula. The characteristic fundoscopic finding is sharply demarcated, circular areas of chorioretinal atrophy that coalesce over time, giving the retina a scalloped appearance. Symptoms typically begin in childhood or early adolescence with night blindness (nyctalopia) and progressive constriction of visual fields. Myopia is common and often severe. Over decades, the atrophic areas enlarge and merge, eventually involving the macula and leading to significant central vision loss, often progressing to legal blindness by the fourth or fifth decade of life. Some patients may also develop posterior subcapsular cataracts, typically in the second or third decade. Additional systemic features can include mild proximal muscle weakness, abnormalities on muscle biopsy showing tubular aggregates in type II muscle fibers, and subtle changes in hair and skin. Mild intellectual disability has been reported in some cases but is not a consistent feature. Treatment focuses on reducing plasma ornithine levels through dietary restriction of arginine (the metabolic precursor of ornithine), as ornithine itself is not a significant dietary component. An arginine-restricted diet has been shown to lower plasma ornithine levels and may slow disease progression, particularly when initiated early in life. A subset of patients (approximately 10-20%) are responsive to pharmacological doses of pyridoxine (vitamin B6), a cofactor for OAT, which can further reduce ornithine levels. Creatine supplementation may also be considered, as creatine synthesis may be impaired due to the metabolic defect. Regular ophthalmologic monitoring is essential for disease management. Gene therapy approaches are under investigation but remain experimental.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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