Methylmalonic AcidemiaSymptoms, Doctors, Treatments, Advances & More
Learn About 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."
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.
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.
Symptoms include:
- Brain damage that gets worse (progressive encephalopathy)
- Dehydration
- Developmental delays
- Failure to thrive
- Lethargy
- Seizures
- Vomiting
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.
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Dr. Hilary Vernon is a Professor of Genetic Medicine and pediatrics at the Johns Hopkins University School of Medicine. She is also an attending physician at Kennedy Krieger Institute. Hilary Vernon has expertise in treating inborn errors of metabolism and mitochondrial disorders. She is the director of the Mitochondrial Care Center at The Johns Hopkins Hospital and the Barth Syndrome Interdisciplinary Clinic at the Kennedy Krieger Institute. Her research interests include understanding intermediary metabolism in Barth syndrome and in disorders of branch chain amino acid metabolism. Dr. Vernon also co-directs the Department of Genetic Medicine Clinical Trials Unit, and is the principal investigator on multiple clinical trials for rare diseases. Dr. Vernon received her medical degree and doctorate from Rutgers University, New Brunswick, New Jersey. She completed residencies in genetics and pediatrics at The Johns Hopkins University, and a fellowship in clinical laboratory biochemical genetics at The Johns Hopkins University. Dr. Vernon was recognized with the 2010 Francis F. Schwentker Award for Excellence in Research at Johns Hopkins University and the 2011 James B. Sidbury Jr. Fellowship in Biochemical Genetics at Johns Hopkins University. Dr. Vernon is rated as an Elite provider by MediFind in the treatment of Methylmalonic Acidemia. Her top areas of expertise are Methylmalonic Acidemia, Propionic Acidemia, Infantile Neutropenia, Progressive External Ophthalmoplegia, and Gastrostomy.
Charles Venditti is a Medical Genetics provider in Bethesda, Maryland. Dr. Venditti is rated as an Elite provider by MediFind in the treatment of Methylmalonic Acidemia. His top areas of expertise are Methylmalonic Acidemia, Propionic Acidemia, Homocystinuria, and Niemann-Pick Disease.
Oleg Shchelochkov is a Medical Genetics specialist and a Pediatrics provider in Iowa City, Iowa. Dr. Shchelochkov is rated as an Elite provider by MediFind in the treatment of Methylmalonic Acidemia. His top areas of expertise are Propionic Acidemia, Argininosuccinic Aciduria, Methylmalonic Acidemia, and Urea Cycle Disorders (UCD).
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.
Complications may include:
- Coma
- Death
- Kidney failure
- Pancreatitis
- Cardiomyopathy
- Recurrent infections
- Hypoglycemia
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
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.
Summary: The primary objective of this study is to evaluate the long-term safety and clinical activity of mRNA-3705 administered to participants with isolated methylmalonic acidemia (MMA) due to methylmalonyl-coenzyme A mutase (MUT) deficiency who have previously participated in other clinical studies of mRNA-3705.
Summary: Methylmalonic acidemia (MMA), one of the most common inborn errors of organic acid metabolism, is heterogeneous in etiology and clinical manifestations. Affected patients with cblA, cblB and mut classes of MMA are medically fragile and can suffer from complications such as metabolic stroke or infarction of the basal ganglia, pancreatitis, end stage renal failure, growth impairment, osteoporosis, a...
Published Date: April 06, 2025
Published 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.