Gyrate atrophy

Gyrate atrophy is a rare, inherited metabolic disorder characterized by progressive loss of vision, and sometimes muscle weakness. It is caused by a deficiency of the enzyme ornithine aminotransferase (OAT), which leads to an excess of the amino acid ornithine in the body.

Symptoms

The first symptom of gyrate atrophy is usually myopia (nearsightedness), which typically begins in early childhood. This is followed by the appearance of circular areas of atrophy in the retina, the light-sensitive layer at the back of the eye. These areas increase in size and number over time, leading to tunnel vision and eventually blindness. Some people with gyrate atrophy also develop cataracts, clouding of the lens of the eye.

In addition to the eye symptoms, about one-third of people with gyrate atrophy have mild muscle weakness and atrophy. This is due to the buildup of ornithine in the muscles.

Causes

Gyrate atrophy is caused by mutations in the OAT gene, which provides instructions for making the enzyme ornithine aminotransferase. This enzyme is involved in the breakdown of the amino acid ornithine. Mutations in the OAT gene reduce or eliminate the activity of this enzyme, leading to an excess of ornithine in the body.

Diagnosis

Gyrate atrophy is diagnosed based on the characteristic eye findings, as well as blood and urine tests that show high levels of ornithine. Genetic testing can confirm the diagnosis.

Treatment

There is currently no cure for gyrate atrophy. Treatment is aimed at slowing the progression of the disease and managing symptoms. This may include a low-protein diet to reduce ornithine levels, vitamin B6 supplements, and glasses or contact lenses to correct myopia.

See also

• Ornithine aminotransferase deficiency
• Retinal diseases
• Metabolic disorders

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