Hyperprolinemia type II

Hyperprolinemia type II is a rare metabolic disorder characterized by an elevated level of the amino acid proline in the blood. This condition is caused by a deficiency in the enzyme Δ1-pyrroline-5-carboxylate dehydrogenase (P5CDH), which is crucial for the metabolism of proline. Hyperprolinemia type II is inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the mutated gene, one from each parent, to be affected by the disorder.

Symptoms and Diagnosis

The symptoms of Hyperprolinemia type II can vary widely among affected individuals. Some may remain asymptomatic, while others can experience neurological and psychiatric manifestations such as seizures, intellectual disability, and schizophrenia-like symptoms. The diagnosis of Hyperprolinemia type II is typically made through biochemical analysis, which reveals elevated levels of proline in the blood and urine. Genetic testing can confirm the diagnosis by identifying mutations in the gene responsible for P5CDH enzyme production.

Treatment

There is no specific treatment for Hyperprolinemia type II. Management of the condition focuses on the symptomatic relief of its manifestations. For example, seizures can be managed with anticonvulsants, and psychiatric symptoms may be treated with appropriate psychotropic medication. Dietary management, including the restriction of proline intake, has been suggested, but its effectiveness is not well established.

Genetics

Hyperprolinemia type II is caused by mutations in the ALDH4A1 gene, which encodes the P5CDH enzyme. This enzyme plays a critical role in the proline degradation pathway, converting Δ1-pyrroline-5-carboxylate to glutamate, a key amino acid in the body's metabolism. The autosomal recessive inheritance pattern means that both copies of the ALDH4A1 gene in each cell have mutations for an individual to express symptoms of the disorder.

Epidemiology

Hyperprolinemia type II is an extremely rare condition, with only a handful of cases reported in the medical literature. Due to its rarity and the variability of its symptoms, it is possible that the disorder is underdiagnosed.

See Also

• Amino acid metabolism disorder
• Inborn errors of metabolism
• Proline
• Autosomal recessive inheritance

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