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

Maple syrup urine disease


Other Names:
Branched chain ketoaciduria; Branched-chain alpha-keto acid dehydrogenase deficiency; BCKD deficiency; Branched chain ketoaciduria; Branched-chain alpha-keto acid dehydrogenase deficiency; BCKD deficiency; Keto acid decarboxylase deficiency; MSUD; BCKDH deficiency; Branched-chain 2-ketoacid dehydrogenase deficiency; Branched-chain ketoaciduria See More
Categories:
Maple syrup urine disease is an inherited disorder in which the body is unable to process certain protein building blocks (amino acids) properly. Beginning in early infancy, this condition is characterized by poor feeding, vomiting, lack of energy (lethargy), seizures, and developmental delay. The urine of affected infants has a distinctive sweet odor, much like burned caramel, that gives the condition its name. Maple syrup urine disease can be life-threatening if untreated.[1]
Last updated: 5/10/2012

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
80%-99% of people have these symptoms
Abnormality of the pharynx 0000600
Abnormality of the voice
Voice abnormality
0001608
Elevated plasma branched chain amino acids 0008344
Global developmental delay 0001263
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific
Mental-retardation
[ more ] 		0001249
Muscular hypotonia
Low or weak muscle tone
0001252
Reduced tendon reflexes 0001315
Respiratory insufficiency
Respiratory impairment
0002093
Seizure 0001250
30%-79% of people have these symptoms
Ataxia 0001251
Hemiplegia/hemiparesis
Paralysis or weakness of one side of body
0004374
Percent of people who have these symptoms is not available through HPO
Autosomal recessive inheritance 0000007
Cerebral edema
Swelling of brain
0002181
Coma 0001259
Feeding difficulties in infancy 0008872
Generalized hypotonia
Decreased muscle tone
Low muscle tone
[ more ] 		0001290
Growth abnormality
Abnormal growth
Growth issue
[ more ] 		0001507
Hallucinations
Hallucination
Sensory hallucination
[ more ] 		0000738
Hypertonia 0001276
Hypoglycemia
Low blood sugar
0001943
Ketosis
High levels of ketone bodies
0001946
Lactic acidosis
Increased lactate in body
0003128
Lethargy 0001254
Pancreatitis
Pancreatic inflammation
0001733
Recurrent 0031796
Vomiting
Throwing up
0002013
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Last updated: 7/1/2020
Maple syrup urine disease is inherited in an autosomal recessive pattern. This means that both copies of a gene in each cell have mutations. The parents of an individual who has the condition each carry one copy of the mutated gene.
Last updated: 4/21/2014

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.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics 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.
  • The Newborn Screening Coding and Terminology Guide has information on the standard codes used for newborn screening tests. Using these standards helps compare data across different laboratories. This resource was created by the National Library of Medicine.
  • 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.

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

  • 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.  

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

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.

Patient Registry

  • A registry supports research by collecting of information about patients that share something in common, such as being diagnosed with Maple syrup urine disease. The type of data collected can vary from registry to registry and is based on the goals and purpose of that registry. Some registries collect contact information while others collect more detailed medical information. Learn more about registries.

    Registries for Maple syrup urine disease:
    NBS Connect
     

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

Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Financial Resources

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 Maple syrup urine disease. This website is maintained by the National Library of Medicine.
  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
  • 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.
  • 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.

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.
  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • MeSH® (Medical Subject Headings) is a terminology tool used by the National Library of Medicine. Click on the link to view information on this topic.
  • 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.
  • The New England Consortium of Metabolic Program has written medical guidelines called acute care protocols for Maple syrup urine disease for health care professionals. 
  • 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 Maple syrup urine disease. Click on the link to view a sample search on this topic.

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

  • I recently began having a maple syrup smell. Is it possible for an adult to develop maple syrup urine disease? How can I get tested? See answer

  • My brother has maple syrup urine disease. Is carrier testing available for individuals from families at risk? See answer


  1. Maple syrup urine disease. Genetics Home Reference. 2008; http://ghr.nlm.nih.gov/condition=maplesyrupurinedisease. Accessed 5/10/2012.