$Unique_ID{BRK03758}
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$Title{Fructose Intolerance, Hereditary}
$Subject{Fructose Intolerance, Hereditary Fructosemia Fructose-1-phosphate
Aldolase Deficiency Fructosuria}
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Copyright (C) 1986, 1987, 1990, 1992 National Organization for Rare Disorders,
Inc.

227:
Fructose Intolerance, Hereditary

** IMPORTANT **
It is possible the main title of the article (Hereditary Fructose
Intolerance) is not the name you expected.  Please check the SYNONYMS listing
to find the alternate names and disorder subdivisions covered by this
article.

Synonyms

     Fructosemia
     Fructose-1-phosphate Aldolase Deficiency
     Fructosuria

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 of this report.


Hereditary Fructose Intolerance is an autosomal recessive genetically caused
inability to digest fructose or its precursors sucrose (sugar, sorbitol and
brown sugar).  This is due to a deficiency of the enzyme
1-phosphofructoaldolase in the liver, kidney cortex and small intestine.

Symptoms

Soon after adding fructose (fruit sugar) to the diet of an infant with
Hereditary Fructose Intolerance, prolonged vomiting, failure to thrive,
occasional unconsciousness, jaundice, and enlargement of the liver, and
tending to bleed because of deficiency of clotting factors may be present.
There will be decreased levels of glucose and phosphate in the blood and
increased levels of fructose in the blood and urine.

Patients with Hereditary Fructose Intolerance usually develop a strong
dislike for sweets and fruit.  There is no intellectual impairment.

It is very important to recognize the intolerance early to avoid damage
to the liver, kidney, and small intestine.

Causes

Hereditary Fructose Intolerance is an autosomal recessively inherited disease
caused by a deficiency of the enzyme 1-phospofructoaldolase.  (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

Hereditary Fructose Intolerance begins at birth and is present in both males
and females.

Related Disorders

Essential Fructosuria is the presence of fructose in the urine after
ingesting fructose, due to a deficiency of the hepatic enzyme fructokinase.
It is an autosomal recessively inherited disorder.

Therapies:  Standard

As long as patients with Hereditary Fructose Intolerance do not ingest
fructose, they can lead a normal life.  However, it is important that this
disorder be diagnosed early so that they can be placed on a special fructose-
free diet to prevent permanent physical damage.

Therapies:  Investigational

Clinical trials are underway to study the metabolic pathogenesis of Fructose
Intolerance.  Interested persons may wish to contact:

     Donald M. Mock, M.D., Ph.D.
     Dept. of Pediatrics, W126 GH
     University of Iowa Hospitals and Clinics
     Iowa City, IA  52242
     (319) 356-3636

to see if further patients are needed for this research.

This disease entry is based upon medical information available through
January 1992.  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 Hereditary Fructose Intolerance, please contact:

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

     National Digestive Diseases Information Clearinghouse
     Box NDIC
     Bethesda, MD  20892
     (301) 468-2162

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

     March of Dimes Birth Defects Foundation
     1275 Mamaroneck Ave.
     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. 2079.

THE METABOLIC BASIS OF INHERITED DISEASE, 6th ed.:  Charles R. Scriver,
et al.; eds., McGraw Hill, 1989.  Pp. 399, 407-13.