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Methylmalonic acidemia (cobalamin disorders)

(meth-uhl-muh-LAHN-ik • a-suh-DEE-mee-uh (koh-BAH-luh-min • disorders))

General Condition Information

Other Names

  • Cobalamin A and B deficiency
  • Cobalamin A, B
  • Cobalamin A,B cofactor deficiency
  • Methylmalonic acidemia
  • Methylmalonic acidemia (Cbl A and Cbl B forms)
  • Methylmalonic acidemia (Cbl A,B)
  • Methylmalonic acidemia (CblA, B)
  • Methylmalonic acidemia (cobalamin conditions)
  • Methylmalonic acidemia (cobalamin disorders A and B)
  • Methylmalonic acidemia (cobalamin disorders, vitamin B12 disorders)
  • Methylmalonic acidemia - Cbl A B
  • Methylmalonic acidemia caused by cobalamin A or cobalamin B deficiencies
  • Methylmalonic acidemia Cbl A and Cbl B forms
  • Methylmalonic acidemia CblA and CblB forms
  • Methylmalonic acidemia cobalamin A, B
  • Methylmalonic acidemia cobalamin disorders
  • Methylmalonic acidemia due to cobalamin A,B defect
  • Methylmalonic acidemia with cobalamin disorders
  • Methylmalonic acidemia, CBl A and B forms
  • Methylmalonic acidemia, cobalamin disorders
  • Methylmalonic acidemia- cobalamin A,B disorders
  • Methylmalonic acidemia- cobalamin defect
  • Methylmalonic acidemia: cobalamin A, B
  • Methylmalonic acidemia: Cobalamin disorders A and B
  • Methylmalonic Acidemia—Cobalamin disorders
  • Methylmalonyl adenosyl- cabalamine synthesis defects

Condition Type

Birth Prevalence

  • This condition is one type of a group of conditions known as methylmalonic acidemias. It is estimated that fewer than 80 babies are born with methylmalonic acidemias each year in the United States.
  • Visit GeneReviews to learn more about how often this condition occurs.

Screening Finding

Increased C3 acylcarnitine (also known as propionyl carnitine) +/- increased methylmalonic and methylcitric acid

What is methylmalonic acidemia (cobalamin disorders)

There are different forms of methylmalonic acidemia, each with different causes and treatments. Methylmalonic acidemias are inherited (genetic) conditions that prevent the body from breaking down certain proteins, cholesterol, and a type of fat called lipids.

Methylmalonic acidemias happen when an enzyme called methylmalonyl CoA mutase (mut) does not work correctly. The mut enzyme uses vitamin B-12 to help digest certain proteins, lipids, and cholesterol to use or get rid of them.

Methylmalonic acidemia (cobalamin disorders) is a type of methylmalonic acidemia that results when vitamin B-12 is not processed correctly, and so cannot help the mut enzyme work. Another type of methylmalonic academia is methylmalonic acidemia (methylmalonyl-CoA mutase).

If your baby does not have enough working mut enzyme, their body has trouble making energy and getting rid of waste. This condition can be more or less severe depending on how well this enzyme works.

If your baby’s body cannot break down proteins, fats, and cholesterol, toxins can build up. When these toxins are acids, blood can become acidic (acidemia). Acidemia can damage your baby’s body and lead to the signs and symptoms of the condition.

Newborn Screening and Follow-Up

Condition Details

Treatment and Management

It is important to talk to your health care provider about which treatment(s) are best for your baby. The goal of treatment is to prevent the health problems caused by this condition. 

Treatments may include the following:

  • Diet low in certain proteins and fats
  • Special formulas and foods for children with methylmalonic acidemia
  • Regular and frequent meals and snacks
  • Vitamin B-12 supplements (only for certain types of methylmalonic acidemia), usually given by a shot (injection) rather than by mouth
  • Carnitine supplements in some cases

Children who receive early intervention and treatment for methylmalonic acidemia can have healthy growth and development. Even with treatment, some children may still have developmental delays or learning difficulties.

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