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Disease Profile

2-methylbutyryl-CoA dehydrogenase deficiency

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

<1 / 1 000 000

US Estimated

Europe Estimated

Age of onset






Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

SBCAD deficiency; 2-methylbutyric aciduria; Short branched-chain acyl-CoA dehydrogenase deficiency


Congenital and Genetic Diseases; Metabolic disorders; Nervous System Diseases;


2-methylbutyryl-CoA dehydrogenase deficiency is an organic acid disorder in which individuals lack adequate levels of an enzyme called 2-methylbutyryl-CoA dehydrogenase. This enzyme assists in the processing of a particular amino acid called isoleucine. The inability to process isoleucine correctly leads to the buildup of the amino acid in the body. The buildup can cause a variety of health problems, which vary widely from severe and life-threatening to mild or absent. Signs and symptoms of the disorder can begin a few days after birth or later in childhood. The initial symptoms often include poor feeding, lack of energy, vomiting, and irritability. These symptoms sometimes progress to serious medical problems such as difficulty breathing, seizures, and coma.[1][[2] This condition is caused by mutations in the ACADSB gene. It is inherited in an autosomal recessive pattern.[1] Treatment, when needed, includes a lowprotein diet, specialty formulas, foods and supplements, and careful observation if illness occurs.[2]


This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
Percent of people who have these symptoms is not available through HPO
Apneic episodes in infancy
Autosomal recessive inheritance
Outward facing eye ball
Generalized amyotrophy
Diffuse skeletal muscle wasting
Generalized muscle degeneration
Muscle atrophy, generalized

[ more ]

Generalized hypotonia
Decreased muscle tone
Low muscle tone

[ more ]

Global developmental delay
Low blood sugar
Abnormally low body temperature
Infantile onset
Onset in first year of life
Onset in infancy

[ more ]

Abnormally small skull
Decreased circumference of cranium
Decreased size of skull
Reduced head circumference
Small head circumference

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Motor delay
Muscular hypotonia
Low or weak muscle tone


Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Newborn Screening


    The resources below provide information about treatment options for this condition. If you have questions about which treatment is right for you, talk to your healthcare professional.

    Management Guidelines

    • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions. Click on the link to view the article on organic acidemias.


      Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

      Organizations Supporting this Disease

        Learn more

        These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

        Where to Start

          In-Depth Information

          • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
          • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
          • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.


            1. 2-methylbutyryl-coenzyme A dehydrogenase deficiency. Genetics Home Reference. April 2007; https://ghr.nlm.nih.gov/condition/2-methylbutyryl-coa-dehydrogenase-deficiency.
            2. 2-methylbutyryl CoA dehydrogenase deficiency. Screening, Technology and Research in Genetics (STAR-G). August 29, 2013; https://www.newbornscreening.info/Parents/organicaciddisorders/2MBC.html.