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$Unique_ID{BRK03965}
$Pretitle{}
$Title{Mannosidosis}
$Subject{Mannosidosis Lysosomal Alpha-D-Mannosidase Deficiency
Mucopolysaccharidosis, Type I Pseudo-Hurler Polydystrophy }
$Volume{}
$Log{}
Copyright (C) 1987, 1988, 1990 National Organization for Rare Disorders,
Inc.
420:
Mannosidosis
** IMPORTANT **
It is possible the main title of the article (Mannosidosis) is not the
name you expected. Please check the SYNONYMS listing on the next page to
find alternate names, disorder subdivisions, and related disorders covered by
this article.
Synonyms
Lysosomal Alpha-D-Mannosidase Deficiency
Information on the following diseases can be found in the Related
Disorders section of this report:
Mucopolysaccharidosis, Type I
Pseudo-Hurler Polydystrophy
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.
Mannosidosis is a genetic disorder characterized by a lysosomal enzyme
deficiency resulting in progressive mental and physical deterioration. A
deficiency of the enzyme alpha-D-mannosidase causes the symptoms of this
disorder which can vary in severity. Symptoms of the most severe form may
begin within the first year of life while a milder form may begin during
juvenile or adult years.
Symptoms
Symptoms of the most severe form of Mannosidosis may begin within the first
year of life. This form is characterized by rapid progression of mental
retardation, liver and spleen enlargement, skeletal abnormalities, and coarse
facial features. A milder form of this disorder involves normal early
development although mild to moderate mental retardation may develop during
childhood or adolescence. The clinical progression of the disease appears to
slow down or stop beyond school age in some patients.
Facial abnormalities such as a prominent forehead and jaw, a flattened
nose, widely spaced or unevenly developed teeth, a thick tongue and lips, and
clouded eye lenses or corneas may develop in both forms of Mannosidosis. The
abdomen may become distended with enlargement of the liver and spleen.
Growth rates can fluctuate with accelerated early growth, but subsequent
impaired growth causing short stature. Thin arms and/or legs with stiff
joints may develop. Spinal abnormalities may lead to extreme curvature in
some cases. A diminished immune system response can make patients overly
susceptible to bacterial infections, particularly of the respiratory system.
Hearing loss may occur in either form of Mannosidosis.
Causes
Mannosidosis is inherited as an autosomal recessive trait. (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.)
Symptoms are caused by an inborn error of enzyme metabolism involving
abnormal accumulations of carbohydrate compounds (mannose-rich glycoproteins
and oligosaccharides) in various tissues and body fluids.
Affected Population
Mannosidosis is a very rare disorder probably affecting only a few hundred
people in the United States. This disorder affects males and females in
equal numbers.
Related Disorders
Symptoms of the following disorders can be similar to Mannosidosis.
Comparisons may be useful for a differential diagnosis:
Mucopolysaccharidoses (MPS disorders) are a group of rare genetic
disorders caused by the deficiency of one of ten specific lysosomal enzymes,
resulting in an inability to metabolize complex carbohydrates
(mucopolysaccharides) into simpler molecules. The accumulation of these
large, undegraded mucopolysaccharides in the cells of the body causes a
number of physical symptoms and abnormalities. A deficiency of the enzyme
alpha-L-iduronidase causes symptoms of Type I MPS disorders. (For more
information on MPS Disorders, choose "MPS" as your search term in the Rare
Disease Database).
Pseudo-Hurler Polydystrophy (Mucolipidosis III) is a genetic disorder
beginning during childhood. This disorder is characterized by symptoms such
as painless joint stiffness, decreased mobility, short stature, some
coarseness of the facial features, mild mental retardation, multiple
defective bone formations, and aortic valve heart disease. Mobility may
gradually diminish until puberty after which no further changes occur.
Pseudo-Hurler Polydystrophy is a milder form of I-cell Disease (Mucolipidosis
II). (For more information on Pseudo-Hurler Polydystrophy, use "I-Cell" as
your search term in the Rare Disease Database).
Therapies: Standard
Treatment of Mannosidosis is symptomatic and supportive. Genetic counseling
may be of benefit for patients and their families.
Therapies: Investigational
Bone marrow transplants as a means of enzyme replacement is under
investigation for treatment of lysosomal storage disorders, such as
Mannosidosis. More research is needed before direct enzyme replacement
therapy or bone marrow transplants can be recommended for use in treating
patients with Mannosidosis.
Pediatric hematologists are developing an international registry for
Blackfan-Diamond Anemia. Families are urged to contact:
Dr. Blanche P. Alter
Mt. Sinai Medical Center
Division of Hematology
One Gustave Levy Place
New York, NY 10029
(212) 241-8109
This disease entry is based upon medical information available through
March 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 Mannosidosis, please contact:
National Organization for Rare Disorders (NORD)
P.O. Box 8923
New Fairfield, CT 06812-1783
(203) 736-6518
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 genetic information 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