Methylmalonyl-CoA mutase deficiency

Methylmalonyl-CoA Mutase Deficiency

Structure of the MUT protein.

Methylmalonyl-CoA mutase deficiency is a rare metabolic disorder that affects the body's ability to break down certain proteins and fats. It is a type of organic acidemia and is caused by a deficiency in the enzyme methylmalonyl-CoA mutase (MUT), which is crucial for the metabolism of certain amino acids and lipids.

Pathophysiology

Methylmalonyl-CoA mutase is an enzyme that catalyzes the conversion of methylmalonyl-CoA to succinyl-CoA, a critical step in the degradation of certain amino acids, such as valine, isoleucine, methionine, and threonine. This reaction is part of the citric acid cycle, which is essential for energy production in cells.

File:Methylmalonyl pathways following amino acid degradation.gif

Pathways following amino acid degradation.

In individuals with methylmalonyl-CoA mutase deficiency, the enzyme is either absent or not functioning properly, leading to the accumulation of methylmalonic acid and other toxic substances in the body. This accumulation can cause a variety of symptoms and complications, including metabolic acidosis, developmental delay, and organ damage.

Clinical Presentation

The clinical presentation of methylmalonyl-CoA mutase deficiency can vary widely among affected individuals. Symptoms may appear in the neonatal period or later in life, depending on the severity of the enzyme deficiency.

Common symptoms include:

• Poor feeding
• Vomiting
• Lethargy
• Hypotonia
• Developmental delay
• Failure to thrive
• Metabolic acidosis

Diagnosis

Diagnosis of methylmalonyl-CoA mutase deficiency is typically made through a combination of clinical evaluation, biochemical testing, and genetic analysis. Elevated levels of methylmalonic acid in the blood and urine are indicative of the disorder.

Treatment

File:Methylmalonyl pathway following methionine and homocysteine degradation.gif

Pathway following methionine and homocysteine degradation.

Treatment for methylmalonyl-CoA mutase deficiency often involves dietary management to limit the intake of certain amino acids that cannot be properly metabolized. In some cases, vitamin B12 (cobalamin) supplementation may be beneficial, particularly in patients with a cobalamin-responsive form of the disorder.

Complications

If left untreated, methylmalonyl-CoA mutase deficiency can lead to serious complications, including:

• Neurological damage
• Chronic kidney disease
• Pancreatitis
• Cardiomyopathy

Related Pages

• Organic acidemia
• Metabolic disorder
• Amino acid metabolism
• Citric acid cycle

The urea cycle, related to amino acid metabolism.

See Also

• Propionic acidemia
• Isovaleric acidemia
• Maple syrup urine disease