Methylmalonic acidemia
Methylmalonic acidemia is a condition in which the body cannot break down certain proteins and fats. The result is a buildup of a substance called methylmalonic acid in the blood. This condition is passed down through families.
It is one of several conditions called an "inborn error of metabolism."
Metabolism
Inborn errors of metabolism are rare genetic (inherited) disorders in which the body cannot properly turn food into energy. The disorders are usuall...
Read Article Now Book Mark ArticleCauses
The disease is most often diagnosed in the first year of life. It is an autosomal recessive condition. This means the variant gene must be passed on to the child from both parents.
A newborn with this rare condition may die before it is ever diagnosed. Methylmalonic acidemia affects boys and girls equally.
Symptoms
Babies may appear normal at birth, but develop symptoms once they start eating more protein, which can cause the condition to get worse. The disease can cause seizures and stroke.
Seizures
A seizure is the physical changes in behavior that occurs during an episode of specific types of abnormal electrical activity in the brain. The term ...
Read Article Now Book Mark ArticleSymptoms include:
- Brain damage that gets worse (progressive encephalopathy)
- Dehydration
- Developmental delays
- Failure to thrive
Failure to thrive
Failure to thrive refers to children whose current weight or rate of weight gain is much lower than that of other children of similar age and sex....
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- Seizures
- Vomiting
Exams and Tests
Testing for methylmalonic acidemia is often done as part of a newborn screening exam. The United States Department of Health and Human Services recommends screening for this condition at birth because early detection and treatment is helpful.
Newborn screening exam
Newborn screening tests look for developmental, genetic, and metabolic disorders in the newborn baby. This allows steps to be taken before symptoms ...
Read Article Now Book Mark ArticleTests that may be done to diagnose this condition include:
- Blood ammonia test
- Blood electrolyte levels
- Blood gases
- Complete blood count
Complete blood count
A complete blood count (CBC) test measures the following:The number of white blood cells (WBC count)The number of red blood cells (RBC count)The numb...
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CT scan
A computed tomography (CT) scan is an imaging method that uses x-rays to create pictures of cross-sections of the body. Related tests include:Abdomin...
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- Methylmalonic acid blood test
- Plasma amino acid test
Plasma amino acid test
Plasma amino acids is a screening test, usually done on infants that looks at the amounts of amino acids in the blood. Amino acids are the building ...
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Treatment
Treatment consists of cobalamin and carnitine supplements and a low-protein diet. The child's diet must be carefully controlled.
If supplements do not help, your child's health care provider may also recommend a diet that avoids substances called isoleucine, threonine, methionine, and valine.
Liver or kidney transplantation (or both) have been shown to help some children. These transplants provide the body with new cells that help breakdown methylmalonic acid normally.
Outlook (Prognosis)
Babies may not survive their first episode of symptoms from this disease. Those who survive often have problems with the development of the nervous system, although normal cognitive development can occur.
Possible Complications
Complications may include:
- Coma
- Death
- Kidney failure
- Pancreatitis
- Cardiomyopathy
Cardiomyopathy
Cardiomyopathy is disease in which the heart muscle becomes weakened, stretched, or has another structural problem. It often contributes to the hear...
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- Hypoglycemia
When to Contact a Medical Professional
Seek medical help right away if your child is having a seizure for the first time.
Contact your child's provider if your child has signs of:
- Failure-to-thrive
- Developmental delays
Prevention
A low-protein diet can help reduce the number of attacks. People with this condition should avoid those who are sick with contagious illnesses, such as colds and the flu.
Genetic counseling may be helpful for couples with a family history of this condition who wish to have a baby.
Sometimes, expanded newborn screening is done at birth, including screening for methylmalonic acidemia. You can ask your provider if your child had this screening.
Reviewed By
Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
Gallagher RC, Enns GM, Cowan TM, Mendelsohn B, Packman S. Aminoacidemias and organic acidemias. In: Swaiman KF, Ashwal S, Ferriero DM, et al, eds. Swaiman's Pediatric Neurology. 6th ed. Elsevier; 2017:chap 37.
Kliegman RM, St. Geme JW, Blum NJ, et al. Defects in metabolism of amino acids. In: Kliegman RM, St. Geme JW, Blum NJ, et al, eds. Nelson Textbook of Pediatrics. 22nd ed. Philadelphia, PA: Elsevier; 2025:chap 105.
Madan-Khetarpal S, Arnold G, Ortiz D. Genetic disorders and dysmorphic conditions. In: Zitelli BJ, McIntire SC, Nowalk AJ, Garrison J, eds. Zitelli and Davis' Atlas of Pediatric Physical Diagnosis. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 1.