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$Unique_ID{BRK03799}
$Pretitle{}
$Title{Hartnup Disease}
$Subject{Hartnup Disease H Disease Hart Syndrome Pellagra-Cerebellar
Ataxia-Renal Aminoaciduria Syndrome Tryptophan Pyrrolase Deficiency
Methylmalonic Aciduria Pellagra}
$Volume{}
$Log{}
Copyright (C) 1987, 1990 National Organization for Rare Disorders, Inc.
347:
Hartnup Disease
** IMPORTANT **
It is possible the main title of the article (Hartnup Disease) is not the
name you expected. Please check the SYNONYMS listing to find the alternate
names, disorder subdivisions, and related disorders covered by this article.
Synonyms
H Disease
Hart Syndrome
Pellagra-Cerebellar Ataxia-Renal Aminoaciduria Syndrome
Tryptophan Pyrrolase Deficiency
Information on the following diseases can be found in the Related Disorders
section of this report:
Pellagra
Methylmalonic Aciduria
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.
Hartnup Disease is a rare metabolic disorder inherited as a recessive
trait. It involves an inborn error of amino acid metabolism as well as
niacin deficiency. Factors which precipitate attacks of this disorder may
include poor nutrition, exposure to sunlight, sulfonamide medications and/or
psychological stress. Hartnup Disease may be marked by skin problems,
coordination impairment, vision problems, mild mental retardation, and
central nervous system abnormalities. Frequency of attacks usually diminish
with age.
Symptoms
Hartnup Disease may be characterized by a red, scaly rash which may occur
after exposure to sunlight. Sudden attacks of impaired muscle coordination
(ataxia), double vision, and fainting may occur with this disorder. Retarded
mental development, short stature, emotional instability, and dementia may
also be symptomatic of untreated Hartnup Disease. Mild heart irregularities
(arrhythmias) may also occur but are extremely rare.
Causes
Hartnup Disease is inherited as a recessive trait. It is an inborn error of
amino acid metabolism including tryptophan (which affects growth), and the
decomposition of these amino acids in the intestines. Precipitating factors
in this disorder may include poor nutrition, fever, exposure to sunlight,
sulfonamide medications and/or psychological stress. (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
Hartnup Disease usually begins in childhood and continues into adulthood.
Like most inborn errors of metabolism, it is very rare.
Related Disorders
Pellagra is an illness that results from a deficiency of nicotinic acid and
occasionally tryptophan. This disorder is marked by lack of appetite
(anorexia), weakness, discomfort, emotional instability, insomnia, bouts of
diarrhea or constipation, a burning or stinging sensation of the skin
(especially following exposure to the sun), and a sore mouth. The skin may
become reddish-brown, scaly, and rough. This disorder usually occurs from
deficiencies in the diet such as those that occur in countries where corn or
maize is the staple food. It is very rare in the United States.
Methylmalonic Aciduria is a form of Ketotic Hyperglycinemia. It is due to a
malfunction of amino acid metabolism. This disorder may be marked by an
accumulation of acid in the blood (acidosis), drowsiness, coma, and mental or
physical retardation. Treatment of Methylmalonic Aciduria includes a
low-protein diet, amino acids such as isoleucine, valine, and threonine and/
or massive doses of Vitamin B-12. (For more information on Ketotic
Hyperglycinemia, choose "hyperglycinemia" as your search term in the Rare
Disease Database.)
Therapies: Standard
Attacks of Hartnup Disease in people affected by this disorder can be reduced
or avoided by maintaining good nutrition, supplementing the diet with
niacinamide or niacin, and avoiding the sun and sulfonamide drugs. Other
treatment is symptomatic and supportive. Genetic counseling may be helpful
to affected families.
Therapies: Investigational
Genetic studies on children born to mothers affected by Hartnup Disease
suggest that the abnormal metabolism of amino acids in this disorder does not
have an adverse effect on the embryo. Further investigations are necessary
to determine the exact biological cause of Hartnup Disease, which could in
turn lead to prevention and/or new treatments.
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 Hartnup Disease, 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 NDDIC
Bethesda, MD 20892
(301) 468-6344
Research Trust for Metabolic Diseases in Children
Golden Gates Lodge, Weston Rd.
Crewe CW1 1XN, England
Telephone: (0270) 250244
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
HARTNUP DISEASE. CLINICAL, PATHOLOGICAL, AND BIOCHEMICAL OBSERVATIONS: A.J.
Tahmoush, et. al.; Arch Neurol. (Dec. 1976, issue 33(12)). Pp.797-807.
MATERNAL HARTNUP DISORDER: B.E. Mahon, et. al.; Am J Med Genet (July 1986,
issue 24(3)). Pp.513-518.
OCCURRENCES OF METHYLMALONIC ACIDURIA AND HARTNUP DISORDER IN THE SAME FAMILY:
V.E. Shih, et. al.; Clin Genet (September 1984, issue 26(3)). Pp. 216-220.