National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

SCOT deficiency


Other Names:
Succinyl-CoA:3-oxoacid CoA transferase deficiency; Ketoacidosis due to SCOT deficiency; Succinyl-CoA acetoacetate transferase deficiency; Succinyl-CoA:3-oxoacid CoA transferase deficiency; Ketoacidosis due to SCOT deficiency; Succinyl-CoA acetoacetate transferase deficiency; 3-oxoacid CoA transferase deficiency See More
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SCOT deficiency is a metabolic disease that is caused by reduced or missing levels of an enzyme called succinyl-CoA:3-ketoacid CoA transferase (SCOT). This enzyme is necessary for the body to use ketones. Ketones are substances produced in the liver when fats are broken down. Ketones are an important source of energy, especially when there is a shortage of carbohydrates (sugar). SCOT deficiency is characterized by episodes of ketoacidosis (build-up of ketones in the body).[1] Symptoms of ketoacidosis may vary but can include trouble breathing, poor feeding, vomiting, and lethargy. In some cases, the symptoms can progress to include loss of consciousness and a coma. In between these episodes, individuals with SCOT deficiency do not have any symptoms.[1]

SCOT deficiency is caused by mutations (changes) in the OXCT1 gene. The disease is inherited in an autosomal recessive manner.[2] SCOT deficiency can be diagnosed by ruling out other causes of ketoacidosis and measuring the level of SCOT enzyme. Genetic testing of the OXCT1 gene can be used to confirm the diagnosis.[1] Immediate treatment of ketoacidotic crises is critical. Treatment options include IV fluids such as glucose and sodium bicarbonate. Frequent meals and eating a diet low in fats is important to reduce the frequency of ketoacidotic crises.[1]
Last updated: 10/7/2017
Symptoms of SCOT deficiency include episodes of ketoacidosis (build-up of ketones in the body). These episodes are often brought on by physical stress, fasting, or illness. The first episode often occurs in newborns or infants between 6-20-months-old.[1] This is because this is often a time when babies begin to eat less frequent meals. Ketones do not need to be broken down by the body until the storage of glucose (sugars) is low. This often happens after about 4 hours of fasting. However, in some cases, babies with SCOT deficiency may have a ketoacidotic episode within the first few days of life.[3]

Symptoms of ketoacidosis may vary but can include rapid breathing (tachypnea), poor feeding, vomiting, and lethargy. In some cases, the symptoms can progress to include seizures, loss of consciousness and a coma.[1][3] The severity of symptoms during ketoacidotic crises can vary. Between crises, individuals with SCOT deficiency have no symptoms. If the disease is properly treated with diet, normal growth and development are expected.[1] 
Last updated: 10/7/2017

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.

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Medical Terms Other Names
Learn More:
HPO ID
Percent of people who have these symptoms is not available through HPO
Autosomal recessive inheritance 0000007
Episodic ketoacidosis 0005974
Ketonuria 0002919
Tachypnea
Increased respiratory rate or depth of breathing
0002789
Vomiting
Throwing up
0002013
Showing of 5 |
Last updated: 7/1/2020
SCOT deficiency is caused by mutations (changes) to the OXCT1 gene. This gene provides the body with instructions for how to create an enzyme called succinyl-CoA:3-ketoacid CoA transferase (SCOT). The SCOT enzyme helps the body break down ketones to be used for energy. When there are mutations in the OXCT1 gene, the body does not make enough of the SCOT enzyme. This causes the body to be unable to break down ketones. When ketones cannot be broken down, they begin to accumulate in the blood and the body does not have enough energy. This causes the symptoms of SCOT deficiency.[3]

It is especially important for the body to be able to break down ketones when there is not other energy available to the body through glucose (sugars). Ketones are most frequently used for energy during times of fasting between meals, illness, or stress. These are the times when symptoms of SCOT deficiency are most likely to occur.[3]  
Last updated: 10/7/2017
SCOT deficiency is inherited in an autosomal recessive manner.[2] This means that both copies of the OXCT1 gene must be changed in order to have symptoms of the disease. We inherit one copy of each gene from our mother and the other from our father. 

People with a mutation in only one copy of the OXCT1 gene are known as carriers. Most carriers do not have any symptoms of the disease, although some may experience ketoacidotic crises during times of stress.[4] When two carriers of SCOT deficiency have children together, for each child there is a:
  • 25% chance that the child will have SCOT deficiency
  • 50% chance that the child will be a carrier of SCOT deficiency like the parents
  • 25% chance that the child will have two working copies of OXCT1, so the child will not have SCOT deficiency and will not be a carrier.
Last updated: 10/7/2017
SCOT deficiency is diagnosed when a child presents with symptoms of the disease during a ketoacidotic crisis. A healthcare provider will then typically complete a series of laboratory tests to rule out other diseases that can cause similar symptoms. Levels of SCOT enzyme can be measured by testing the cells of the skin (fibroblasts). If these enzyme levels are low, it indicates that a child has SCOT deficiency. Genetic testing of the OXCT1 gene can be used to confirm the diagnosis.[1]
Last updated: 10/8/2017

Testing Resources

  • Orphanet lists international laboratories offering diagnostic testing for this condition.
The treatment for SCOT deficiency is based on trying to avoid ketoacidotic crises, as these are the only times that symptoms of the disease occur. Because ketoacidotic crises occur when all of the glucose from a meal is broken down, it is important for people with SCOT deficiency to eat frequent meals with large amounts of carbohydrates. It is also important for people with SCOT deficiency to avoid eating food with high fat content. Doctors may recommend that people with the disease avoid high-protein meals as well. Individuals with SCOT deficiency can monitor levels of ketones in the urine in order to make sure they are not too high. Oral sodium bicarbonate supplements can be used in times of stress, such as an illness, to make sure that the body is receiving enough energy from other forms.[1] 

If a ketoacidotic crisis does occur, it is important that people with SCOT deficiency receive treatment right away. People with this disease typically respond well to IV infusions of glucose and sodium bicarbonate during times of ketoacidotic crisis.[1]
Last updated: 10/8/2017

Management Guidelines

  • Orphanet Emergency Guidelines is an article which is expert-authored and peer-reviewed that is intended to guide health care professionals in emergency situations involving this condition.  
The long-term outlook for children with SCOT deficiency can vary. For some children, the initial presentation of symptoms can be very severe. If a diagnosis of SCOT deficiency and treatment is not received, the initial symptoms can be fatal. In some cases, people with SCOT deficiency may develop heart problems. As children get older, the frequency of episodes tends to decrease.[5] 

If the recommended diet is followed and precautions are taken during times of stress on the body such as illness, the long-term outlook for people affected by SCOT deficiency is good. With proper management, children with SCOT deficiency are expected to reach their developmental milestones at the appropriate age, and intellectual disability is not known to be associated with the disease. A good outcome is predicted even in individuals who have multiple ketoacidotic crises.[6] 
Last updated: 10/8/2017

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
Differential diagnoses include physiological ketosis (e.g. ketoacidosis due to significant catabolism due to rotavirus infection) and ketoacidosis due to beta-ketothiolase deficiency or monocarboxylate transporter 1 deficiency.
Visit the Orphanet disease page for more information.

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • The U.S. National Institutes of Health, through the National Library of Medicine, developed ClinicalTrials.gov to provide patients, family members, and members of the public with current information on clinical research studies. There is a study titled Pediatric Patients With Metabolic or Other Genetic Disorders which may be of interest to you.
  • Orphanet lists European clinical trials, research studies, and patient registries enrolling people with this condition. 

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

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.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss SCOT deficiency. Click on the link to view a sample search on this topic.

Selected Full-Text Journal Articles

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • My son has frequent ketosis and occasional ketoacidosis. He has a diagnosis of ketotic hypoglycemia, but seems to have a lot of non-fasting ketotic vomiting episodes. I believe that he may have SCOT deficiency. Would SCOT deficiency cause abnormal amino acid, organic acid or carnitine results? If not, what type of lab work would support a diagnosis of this deficiency? How is the diagnosis of SCOT deficiency confirmed? What kind of lab results would you expect from a patient with SCOT deficiency while they are in crisis? How common is SCOT deficiency? How can I find a doctor or clinic that is familiar with this deficiency? 
    See answer


  1. Fukao T. Succinyl-CoA : 3-ketoacid CoA transferase (SCOT deficiency). Orphanet Encyclopedia. September 2004; http://www.orpha.net/data/patho/GB/uk-scot.pdf.
  2. Succinyl-CoA:3-Oxoacid-CoA Transferase Deficiency; SCOTD. Online Mendelian Inheritance in Man. May 22, 2015; https://www.omim.org/entry/245050.
  3. Succinyl-CoA:3-ketoacid CoA transferase deficiency. Genetics Home Reference. December 2011; https://ghr.nlm.nih.gov/condition/succinyl-coa3-ketoacid-coa-transferase-deficiency.
  4. Sasai H, Aoyama Y, Otsuka H, Abdelkreem E, Naiki Y, Kubota M, Sekine Y, Itoh M, Nakama M, Ohnishi H, Fujiki R, Ohara O, and Fukao T. Heterozygous carriers of succinyl-CoA:3 oxoacid CoA transferase deficiency can develop severe ketoacidosis. Journal of Inherited Metabolic Disease. July 10, 2017; https://www.ncbi.nlm.nih.gov/pubmed/28695376.
  5. Fukao T. Succinyl-CoA:3-ketoacid CoA transferase deficiency. Orphanet. September 2013; http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=832.
  6. Fukao T, Sass JO, Kursula P, Thimm E, Wendel U, Ficicoglu C, Monastiri K, Guffon N, Baric I, Zabot MT, and Kondo N. Clinical and molecular characterization of five patients with succinyl-CoA:3-ketoacid CoA transferase (SCOT) deficiency. Biochimica et Biophysica Acta. May 2011; 1812(5):619-624. https://www.ncbi.nlm.nih.gov/pubmed/21296660.