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$Title{Maple Syrup Urine Disease}
$Subject{Maple Syrup Urine Disease Ketoaciduria Branched Chain Ketonuria
Menke's Syndrome I }
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Copyright (C) 1986, 1990 National Organization for Rare Disorders, Inc.

131:
Maple Syrup Urine Disease

** IMPORTANT **
It is possible that the main title of the article (Maple Syrup Urine
Disease) is not the name you expected.  Please check the SYNONYM listing to
find the synonyms and disorder subdivisions covered by this article.

Synonyms

     Ketoaciduria
     Branched Chain Ketonuria
     Menke's Syndrome I

General Discussion

** REMINDER **
The information contained in the Rare Disease Database is provided for
educational purposes only.  It should not be used for diagnostic or treatment
purposes.  If you wish to obtain more information about this disorder, please
contact your personal physician and/or the agencies listed in the "Resources"
section.


Maple syrup urine disease results from abnormal metabolism of the four
"branched chain" amino acids (protein building blocks), leucine, isoleucine,
valine, and alloisoleucine.  Spasticity alternating with poor muscle tone,
convulsions, and possibly fatal coma characterize the disease.  It derives
its name from the odor of patients' urine and sweat.  Maple syrup urine
disease is a hereditary condition.

Symptoms

Newborns afflicted with Maple syrup urine disease appear normal at first, but
develop symptoms several days later.  These include the characteristic odor
of sweat and urine, poor feeding, lethargy, and lack of awareness or
alertness.  Brain damage can occur rapidly and is manifested by spasticity or
excessively strong reflexes alternating with periods of flaccidity.  If the
infant survives past a few months, mental retardation becomes apparent.

Blood tests reveal high levels of leucine, isoleucine, and valine.

Causes

Maple syrup urine disease results from a defective enzyme blocking the
decarboxylation of branched chain keto-acids, which include the amino acids
leucine, isoleucine, valine, and alloisoleucine.  The excessive accumulation
of these substances cause severe neurological damage.

The disorder is transmitted by an autosomal recessive gene.  (Human
traits including the classic genetic diseases, are the product of the
interaction of two genes for that condition, one received from the father and
one from the mother.  In recessive disorders, the condition does not appear
unless a person inherits the same defective gene from each parent.  If one
receives one normal gene and one gene for the disease, the person will be a
carrier for the disease, but usually will show no symptoms.  The risk of
transmitting the disease to the children of a couple, both of whom are
carriers for a recessive disorder, is twenty-five percent.  Fifty percent of
their children will be carriers, but healthy as described above.  Twenty-five
percent of their children will receive both normal genes, one from each
parent and will be genetically normal.)

Affected Population

Both sexes are affected.  Maple syrup urine disease is extremely rare.

Therapies:  Standard

Treatment of Maple Syrup Urine Disease should start as early as possible
after birth.  Toxins are removed by peritoneal dialysis with exchange
transfusions lacking leucine, isoleucine, and valine, or with multiple or
prolonged exchange transfusions.  Positive calorie supplementation is also
recommended.  Children with this disorder must stay on a strict diet
established by a physician avoiding certain amino acids.

Therapies:  Investigational

This disease entry is based upon medical information available through
January 1990.  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.

Resources

For more information on Maple Syrup Urine Disease, please contact:

     National Organization for Rare Disorders (NORD)
     P.O. Box 8923
     New Fairfield, CT  06812-1783
     (203) 746-6518

     Families with Maple Syrup Urine Disease
     Route 2, Box 24-A
     Flemingsburg, KY 41041
     (606) 849-4679

     Research Trust for Metabolic Diseases in Children
     Golden Gates Lodge, Weston Rd.
     Crewe CW1 1XN, England
     Telephone:  (0270) 250244

     National Digestive Diseases Information Clearinghouse
     Box NDDIC
     Bethesda, MD  20892
     (301) 468-6344

For information on genetics and genetic counseling referrals, please
contact:

     March of Dimes Birth Defects Foundation
     1275 Mamaroneck Avenue
     White Plains, NY  10605
     (914) 428-7100

     Alliance of Genetic Support Groups
     35 Wisconsin Circle, Suite 440
     Chevy Chase, MD  20815
     (800) 336-GENE
     (301) 652-5553

References

THE MERCK MANUAL 15th ed:  R. Berkow, et al:  eds; Merck, Sharp & Dohme
Research Laboratories, 1987.  P. 2084.

CECIL TEXTBOOK OF MEDICINE, 18th ed.:  James B. Wyngaarden, and Lloyd H.
Smith, Jr., Eds.:  W. B. Saunders Co., 1988.  Pp. 1150, 1159.