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Disease Profile

Short-chain acyl-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.


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)

SCAD deficiency; ACADS deficiency; SCADH deficiency;


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


Short-chain acyl-CoA dehydrogenase (SCAD) deficiency is a rare genetic condition that prevents the body from converting certain fats (called short-chain fatty acids) into energy.[1] This condition belongs to a group of disorders known as fatty acid oxidation disorders (FOD).[2] SCAD deficiency is caused by mutations in the ACADS gene.[1] These mutations lead to a shortage (deficiency) of an enzyme known as short-chain acyl-CoA dehydrogenase, which is involved in the breakdown of short-chain fatty acids. When not enough of this enzyme is present, excessive amounts of fatty acids and ammonia accumulate in the body.[1][2] The symptoms of SCAD deficiency include a lack of energy, poor growth, and developmental delay.[1] Treatment for this condition typically includes a low-fat diet and avoidance of long periods without food (fasting).[2]


Some infants and children with SCAD deficiency may exhibit vomiting, low blood sugar (hypoglycemia), a lack of energy (lethargy), poor feeding, and failure to gain weight and grow at the expected rate (failure to thrive). Other features of this disorder may include poor muscle tone (hypotonia), seizures, developmental delay, and a small head size (microcephaly). The symptoms of SCAD deficiency may be triggered by periods of fasting or during illnesses such as viral infections. In some cases, signs and symptoms may not appear until adulthood, when some individuals may develop muscle weakness and wasting. Some people are never diagnosed because they have very mild symptoms.[1]

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:
5%-29% of people have these symptoms
Progressive external ophthalmoplegia
Percent of people who have these symptoms is not available through HPO
Abnormality of the cerebral white matter
Autosomal recessive inheritance
Disease of the heart muscle
Delayed speech and language development
Deficiency of speech development
Delayed language development
Delayed speech
Delayed speech acquisition
Delayed speech development
Impaired speech and language development
Impaired speech development
Language delay
Language delayed
Language development deficit
Late-onset speech development
Poor language development
Speech and language delay
Speech and language difficulties
Speech delay

[ more ]

Episodic metabolic acidosis
Ethylmalonic aciduria
Facial palsy
Bell's palsy
Failure to thrive
Faltering weight
Weight faltering

[ more ]

Feeding difficulties in infancy
Flexion contracture
Flexed joint that cannot be straightened
Generalized hypotonia
Decreased muscle tone
Low muscle tone

[ more ]

Global developmental delay
Muscular hypotonia
Low or weak muscle tone
Muscle tissue disease
Neonatal onset


Mutations in the ACADS gene cause SCAD deficiency. These mutations lead to inadequate levels of an enzyme called short-chain acyl-CoA dehydrogenase. This enzyme is important for the breakdown of a particular type of fat called short-chain fatty acids. Reduced levels of this enzyme prevent short-chain fatty acids from being further broken down and processed in the mitochondria (the energy-producing centers inside cells). As a result, these short-chain fatty acids are not converted into energy, which can lead to the signs and symptoms of this disorder, such as lethargy, hypoglycemia, and muscle weakness.[1]


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

  • An ACTion (ACT) sheet is available for this condition that describes the short-term actions a health professional should follow when an infant has a positive newborn screening result. ACT sheets were developed by experts in collaboration with the American College of Medical Genetics.
  • An Algorithm flowchart is available for this condition for determining the final diagnosis in an infant with a positive newborn screening result. Algorithms are developed by experts in collaboration with the American College of Medical Genetics.
  • Baby's First Test is the nation's newborn screening education center for families and providers. This site provides information and resources about screening at the local, state, and national levels and serves as the Clearinghouse for newborn screening information.
  • National Newborn Screening and Global Resource Center (NNSGRC) provides information and resources in the area of newborn screening and genetics to benefit health professionals, the public health community, consumers and government officials.


    Treatment of short-chain acyl-CoA dehydrogenase (SCAD) deficiency usually consists of avoidance of fasting and a low fat diet. Supplemental carnitine may be recommended for some affected children during acute crises. Episodes of acute metabolic acidosis may be treated with intravenous hydration with a solution containing 10% glucose which can reestablish an anabolic state. This can be followed by reintroduction of the patient's usual diet.[2]


    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

      Organizations Providing General Support

        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

        • Genetics Home Reference (GHR) contains information on Short-chain acyl-CoA dehydrogenase deficiency. This website is maintained by the National Library of Medicine.
        • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.
        • Save Babies Through Screening Foundation's website has an information page on short-chain acyl-coenzyme A dehydrogenase (SCAD) deficiency. Click on Save Babies Through Screening Foundation to view this information page.
        • The Screening, Technology And Research in Genetics (STAR-G) Project has a fact sheet on this condition, which was written specifically for families that have received a diagnosis as a result of newborn screening. This fact sheet provides general information about the condition and answers questions that are of particular concern to parents.
        • The Muscular Dystrophy Association has developed a resource called "Facts About Myopathies" that discusses commonly asked questions regarding myopathies. Click on the link above to view this information page.

          In-Depth Information

          • 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.
          • 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.
          • PubMed is a searchable database of medical literature and lists journal articles that discuss Short-chain acyl-CoA dehydrogenase deficiency. Click on the link to view a sample search on this topic.

            Selected Full-Text Journal Articles


              1. Short-chain acyl-CoA dehydrogenase deficiency. Genetics Home Reference (GHR). May 2015; https://ghr.nlm.nih.gov/condition/short-chain-acyl-coa-dehydrogenase-deficiency.
              2. Jerry Vockley, MD, PhD. Short-Chain Acyl CoA Dehydrogenase Deficiency (SCAD). National Organization for Rare Disorders (NORD). 2013; https://rarediseases.org/rare-diseases/short-chain-acyl-coa-dehydrogenase-deficiency-scad/.

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