Methylmalonic aciduria

Methylmalonic aciduria is a genetic disorder that affects the body's ability to metabolize certain proteins and lipids. It is a type of organic acidemia, which is characterized by an excess of organic acids in the body. The condition is inherited in an autosomal recessive manner, meaning both parents must carry a copy of the mutated gene for a child to be affected.

Causes

Methylmalonic aciduria is caused by mutations in the MUT gene, which provides instructions for making an enzyme called methylmalonyl CoA mutase. This enzyme is necessary for the breakdown of certain amino acids and lipids. When the MUT gene is mutated, the enzyme's activity is reduced or absent, leading to a buildup of methylmalonic acid in the body.

Symptoms

Symptoms of methylmalonic aciduria can vary widely, but they often include failure to thrive, developmental delay, chronic kidney disease, and pancreatitis. Other symptoms can include vomiting, dehydration, hypotonia (low muscle tone), seizures, and intellectual disability.

Diagnosis

Diagnosis of methylmalonic aciduria is typically made through genetic testing, which can identify mutations in the MUT gene. Other diagnostic tests may include urine tests to detect elevated levels of methylmalonic acid, and blood tests to check for high levels of ammonia and other abnormal substances.

Treatment

There is currently no cure for methylmalonic aciduria, but treatment can help manage symptoms and prevent complications. Treatment typically involves a low-protein diet to reduce the amount of methylmalonic acid produced in the body. Some patients may also require vitamin B12 supplements, as this vitamin is a cofactor for methylmalonyl CoA mutase. In severe cases, a kidney transplant or liver transplant may be necessary.

Prognosis

The prognosis for individuals with methylmalonic aciduria varies depending on the severity of the condition and the individual's response to treatment. With early diagnosis and appropriate management, many individuals with this condition can lead relatively normal lives.

See also

• Organic acidemia
• Inborn errors of metabolism
• MUT gene

NIH genetic and rare disease info

• NIH info on Methylmalonic aciduria

Methylmalonic aciduria is a rare disease.

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