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$Unique_ID{BRK04220}
$Pretitle{}
$Title{Sialidosis}
$Subject{Sialidosis Cherry Red Spot Myoclonus syndrome Mucolipidosis I ML I
Lipomucopolysaccharidosis Type I Sialidosis Type I Sialidosis Type II}
$Volume{}
$Log{}
Copyright (C) 1986, 1990 National Organization for Rare Disorders, Inc.
302:
Sialidosis
** IMPORTANT **
It is possible the main title of the article (Sialidosis) is not the name
you expected. Please check the SYNONYMS listing to find the alternate names
and disorder subdivisions covered by this article.
Synonyms
Cherry Red Spot - Myoclonus syndrome
Mucolipidosis I
ML I
Lipomucopolysaccharidosis Type I
DISORDER SUBDIVISIONS
Sialidosis Type I
Sialidosis Type II
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.
The Mucolipidoses (ML II & ML III) are a family of hereditary disorders
in which enzyme deficiencies cause both complex carbohydrates
(mucopolysaccharides) and certain fatty substances (mucolipids) to accumulate
in body tissues without excess mucopolysaccharides in the urine. (For more
information on the mucolipidoses, choose "ML Disorder" as your search term in
the Rare Disease Database.)
Sialidosis (previously called Mucolipidosis I) is a very rare recessive
hereditary disorder caused by decreased activity of the enzyme gamma-
neuraminidase. Patients have normal urinary mucopolysaccharides, elevated
urinary oligosaccharides containing salic acid, mild mental retardation,
cherry-red spots on the retina (interior back portion of the eyeball), and
signs of neurological involvement in older children.
Two forms of Sialidosis are known. Sialidosis Type I has primary eye and
muscle involvement (myoclonus). Sialidosis Type II has eye and muscle
involvement plus mild coarsening of the face, skeletal changes and mild
mental retardation.
Symptoms
Sialidosis (Lipomucopolysaccharidosis Type I) is characterized by moderate
developmental retardation which usually occurs during late infancy. As the
disease progresses, the children manifest short stature with a
disproportionately short trunk, an enlarged liver and spleen
(hepatosplenomegaly), hernias, moderate to severe mental retardation,
impaired hearing and cherry-red macular spots on the retina of the eye.
Progressive loss of vision, often severe, may be associated with impaired
color vision or night blindness.
After about 5 years, there are progressive signs of a dysfunction of the
white matter of the nervous system such as seizures with shocklike muscular
contractions (myoclonus); decreased muscle strength; diminished tonus of the
muscles (hypotonia); uncoordinated movements (ataxia); tremor; rapid
movements of the eyeballs (nystagmus); irregular reflexes; and reduced nerve
conduction velocity.
In older patients, the electro-encephalogram (EEG) shows peculiar
complexes of high-frequency polyspikes and sharp waves. Generalized abnormal
bone development occurs. Opacities of the cornea of the eye may sometimes
develop.
Causes
Sialidosis is an autosomal recessive inherited disorder in which the activity
of the enzyme gamma-neuraminidase is deficient. (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
Sialidosis affects males as often as females. Siblings of patients have a 1
in 4 chance to be affected.
Therapies: Standard
Carriers of Sialidosis can be detected by an enzyme assay in cultured
fibroblasts, making prenatal diagnosis possible. Genetic counseling is
advised for families affected by this disorder.
Treatment of Sialidosis is symptomatic and supportive. Seizures may be
controlled by a variety of anticonvulsant medications.
Therapies: Investigational
Since prenatal diagnosis is now possible through amniocentesis and sampling
of a tissue layer in the embryo (chorionic villus sampling), new treatments
aimed at checking early development of Sialidosis are now under
investigation. One method involves replacing defective enzymes via enzyme
replacement therapy and/or bone marrow transplants. Scientific study of gene
replacement in animal models raises the hope that gene replacement therapy
may someday be made available to people with genetic disorders such as
Sialidosis.
This disease entry is based upon medical information available through
February 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 Sialidosis, please contact:
National Organization for Rare Disorders (NORD)
P.O. Box 8923
New Fairfield, CT 06812-1783
(203) 746-6518
MPS (Mucopolysaccharidoses) Research Funding Center, Inc.
1215 Maxfield Road
Hartland, MI 48029
(313) 363-4412
The MPS Society, Inc.
17 Kramer Street
Hicksville, NY 11801
(516) 931-6338
Society of Mucopolysaccharide Diseases, Inc.
382 Parkway Blvd.
Flin Flon, Manitoba, Canada R8A 0K4
Society of MPS Diseases
30 Westwood Drive
Little Chalfont, Bucks, England
National Digestive Diseases Information Clearinghouse
Box NDDIC
Bethesda, MD 20892
(301) 468-6344
International Tremor Foundation
360 W. Superior St.
Chicago, IL 60610
(312) 664-2344
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
BIRTH DEFECTS COMPENDIUM, 2d ed.: Daniel Bergsma, ed.; March of Dimes, 1979.
P. 724.
MENDELIAN INHERITANCE IN MAN, 6th ed.: Victor A. McKusick; Johns Hopkins
University Press, 1983. Pp. 832-833.