Hyperornithinemia

Hyperornithinemia is a rare metabolic disorder characterized by abnormally high levels of the amino acid ornithine in the blood. Ornithine is a building block of proteins and plays a role in various metabolic pathways, including the urea cycle, which is responsible for detoxifying ammonia. There are two main forms of hyperornithinemia: the classical form and the gyrate atrophy form.

The classical form of hyperornithinemia is often benign, meaning it may not cause significant health problems. Some individuals may experience mild symptoms like muscle weakness or neurological issues, but many are asymptomatic.

The gyrate atrophy form is a more severe condition associated with a deficiency in the enzyme ornithine delta-aminotransferase. This deficiency leads to a buildup of ornithine and a lack of a functional enzyme required for the breakdown of arginine. The most prominent symptom of gyrate atrophy is progressive chorioretinal degeneration, which affects the eyes and can lead to severe vision impairment, including myopia, cataracts, and eventually blindness. Other potential symptoms can include muscle atrophy and neurological abnormalities.

Diagnosis of hyperornithinemia is typically made through blood tests that measure ornithine levels. Genetic testing can confirm the specific form of the disorder. Treatment strategies vary depending on the type. For the gyrate atrophy form, dietary restrictions low in arginine and protein, along with vitamin B6 supplementation, may help slow disease progression. Management focuses on symptom control and preventing complications.