Overview
Gyrate atrophy is a rare autosomal recessive chorioretinal dystrophy caused by deficiency of ornithine aminotransferase (OAT), leading to accumulation of ornithine in plasma and tissues. It presents with sharply demarcated circular areas of chorioretinal atrophy that progressively enlarge and coalesce, causing night blindness, peripheral field loss, and eventual central vision impairment. Systemic manifestations include type II muscle fiber atrophy.
Genetics
Caused by OAT mutations affecting ornithine metabolism. Over 60 mutations identified. Inheritance is autosomal recessive.
| Gene | Locus | Inheritance | Notes |
|---|---|---|---|
| OAT | 10q26.13 | AR | Ornithine aminotransferase; sole known cause |
Clinical Presentation
Childhood–adolescence
- Night blindness
- Myopia (often high)
- Peripheral visual field loss beginning
Young adulthood
- Progressive chorioretinal atrophy
- Posterior subcapsular cataracts
- Tunnel vision
Advanced
- Severe visual field loss
- Central vision loss
- Legal blindness typically by 4th–5th decade
Diagnosis
- Plasma ornithine: Markedly elevated (10–20x normal) — diagnostic
- Fundus: Circular, scalloped areas of chorioretinal atrophy in mid-periphery
- ERG: Reduced rod and cone responses
- Genetic testing: OAT sequencing
- Muscle biopsy: Type II fiber atrophy (optional)
Current Research & Treatment
Dietary arginine restriction reduces plasma ornithine and may slow progression. Vitamin B6 (pyridoxine) supplementation benefits a subset of patients with B6-responsive mutations. Gene therapy for OAT is in preclinical development.
Active Clinical Trials
The following active clinical trials are investigating treatments for Gyrate Atrophy of the Choroid and Retina. Trial status and enrollment may change; always verify directly on ClinicalTrials.gov.