Maple Syrup Urine Disease

Synonyms

• BCKD Deficiency
• Branched Chain Alpha-Ketoacid Dehydrogenase Deficiency
• Branched Chain Ketonuria I
• Classical Maple Syrup Urine Disease
• MSUD

Disorder Subdivisions

• Intermittent Maple Syrup Urine Disease
• Intermediate Maple Syrup Urine Disease
• Thiamine-Responsive Maple Syrup Urine Disease
• Classic Maple Syrup Urine Disease

General Discussion

Maple syrup urine disease (MSUD) is a rare genetic disorder characterized by deficiency of certain enzymes (branched-chain alpha-keto acid dehydrogenase complex) required to breakdown (metabolize) specific amino acids in the body. Because these amino acids are not metabolized, they, along with their various byproducts, abnormally accumulate in the cells and fluids of the body. Such accumulation can cause a variety of symptoms including lethargy, irritability, poor feeding, abnormal movements and a characteristic odor of maple syrup in the earwax (cerumen), sweat and urine of affected individuals. In addition, if untreated various neurological complications including seizures, coma and brain damage may occur. Failure to promptly detect and treat MSUD can lead to life-threatening complications. However, the disorder can be successfully managed through a specialized diet. Even with treatment affected individuals remain at risk for developing episodes of acute illness (metabolic crisis) often triggered by infection, injury, failure to eat (fasting) or psychological stress. During these episodes there is a rapid, sudden spike in amino acid levels necessitating immediate medical intervention.

At least four subtypes of MSUD have been identified in the medical literature. Some researchers include a fifth subtype, although other researchers consider this a separate distinct disorder. The various subtypes of MSUD have different levels of residual enzyme activity, different severity, and different ages of onset. All forms are inherited as autosomal recessive traits.

Resources

CLIMB (Children Living with Inherited Metabolic Diseases)
Climb Building
176 Nantwich Road
Crewe, Intl CW2 6BG
United Kingdom
Tel: +44 870 7700 325
Fax: +44 870 7700 327
Email: info@climb.org.uk
Internet: http://www.CLIMB.org.uk

March of Dimes Birth Defects Foundation
1275 Mamaroneck Avenue
White Plains, NY 10605
Tel: (914)428-7100
Fax: (914)997-4763
Tel: (888)663-4637
Email: Askus@marchofdimes.com
Internet: http://www.marchofdimes.com

The Arc (a national organization on mental retardation)
1010 Wayne Ave
Suite 650
Silver Spring, MD 20910
Tel: (301)565-3842
Fax: (301)565-3843
Tel: (800)433-5255
TDD: (817)277-0553
Email: info@thearc.org
Internet: http://www.thearc.org/

NIH/National Digestive Diseases Information Clearinghouse
2 Information Way
Bethesda, MD 20892-3570
Tel: (301)654-3810
Fax: (301)907-8906
Tel: (800)891-5389
Email: nddic@info.niddk.nih.gov
Internet: http://www.niddk.nih.gov

Maple Syrup Urine Disease Family Support Group
82 Ravine Road
Powell, OH 43065
United States
Tel: 7405484475
Email: dbulcher@aol.com
Internet: http://www.msud-support.org/

Belgian Association for Metabolic Diseases (BOKS)
Alice Nahonlann 7
Melsele, 9120
Belgium
Tel: 3237754839
Email: info@boks.be
Internet: http://www.boks.be

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders, Inc. ® (NORD). A copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians.

It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report.

This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

For additional information and assistance about rare disorders, please contact the National Organization for Rare Disorders at P.O. Box 1968, Danbury, CT 06813-1968; phone (203) 744-0100; web site www.rarediseases.org or email orphan@rarediseases.org

Last Updated: 8/7/2007
Copyright 1986, 1990, 1994, 1999, 2000, 2002, 2007 National Organization for Rare Disorders, Inc.