Malonic aciduria

A rare metabolic disorder

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Malonic aciduria, also known as malonyl-CoA decarboxylase deficiency, is a rare metabolic disorder characterized by the accumulation of malonic acid in the body. This condition is caused by a deficiency in the enzyme malonyl-CoA decarboxylase, which is crucial for the proper metabolism of certain fatty acids.

Pathophysiology

Diagram of malonyl-CoA, a key molecule in fatty acid metabolism.

Malonic aciduria results from a deficiency in the enzyme malonyl-CoA decarboxylase, which is responsible for converting malonyl-CoA to acetyl-CoA and carbon dioxide. This enzyme deficiency leads to the accumulation of malonyl-CoA and malonic acid, disrupting normal fatty acid metabolism. The accumulation of these substances can interfere with energy production and other metabolic processes, leading to the symptoms observed in affected individuals.

Clinical Presentation

Individuals with malonic aciduria may present with a variety of symptoms, which can vary in severity. Common clinical features include:

• Developmental delay
• Hypotonia (reduced muscle tone)
• Seizures
• Cardiomyopathy
• Metabolic acidosis
• Failure to thrive

The onset of symptoms can occur in infancy or early childhood, and the severity can range from mild to life-threatening.

Genetics

Diagram showing autosomal recessive inheritance.

Malonic aciduria is inherited in an autosomal recessive pattern, meaning that an individual must inherit two copies of the defective gene, one from each parent, to be affected by the disorder. The gene responsible for this condition is located on chromosome 16 and is known as MLYCD, which encodes the malonyl-CoA decarboxylase enzyme.

Diagnosis

The diagnosis of malonic aciduria is typically made based on clinical symptoms, biochemical testing, and genetic analysis. Key diagnostic tests include:

• Measurement of malonic acid levels in the urine and blood
• Enzyme assay to assess malonyl-CoA decarboxylase activity
• Genetic testing to identify mutations in the MLYCD gene

Management

There is currently no cure for malonic aciduria, and treatment is primarily supportive and symptomatic. Management strategies may include:

• Dietary modifications to reduce the intake of certain fatty acids
• Supplementation with carnitine to enhance fatty acid metabolism
• Medications to manage seizures and other symptoms
• Regular monitoring and supportive care to address developmental and metabolic needs

Prognosis

The prognosis for individuals with malonic aciduria varies depending on the severity of the enzyme deficiency and the effectiveness of management strategies. Early diagnosis and intervention can improve outcomes and quality of life for affected individuals.

Related pages

• Metabolic disorder
• Fatty acid metabolism
• Genetic disorder