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$Unique_ID{BRK04008}
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$Title{Morquio Syndrome}
$Subject{Morquio Syndrome Mucopolysaccharidosis IV MPS IV Morquio Disease
Morquio Syndrome A Galactosamine-6-Sulfatase Deficiency Morquio-Brailsford
Syndrome Osteochondrodystrophy Deformans Chondroosteodystrophy Morquio
Syndrome B Beta-Galactosidase Deficiency Morquio Syndrome}
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Copyright (C) 1986, 1987, 1988, 1990 National Organization for Rare
Disorders, Inc.

299:
Morquio Syndrome

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

Synonyms

     Mucopolysaccharidosis IV
     MPS IV
     Morquio Disease

DISORDER SUBDIVISIONS

     Morquio Syndrome A
     Galactosamine-6-Sulfatase Deficiency
     Morquio-Brailsford Syndrome
     Osteochondrodystrophy Deformans
     Chondroosteodystrophy
     Morquio Syndrome B
     Beta-Galactosidase Deficiency Morquio Syndrome

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.


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.

Morquio Syndrome (MPS IV) exists in 2 forms:
Morquio Syndromes A and B are due to a deficiency in the enzyme N-acetyl-
galactosamine-6-sulfatase and beta-galactosidase, respectively.  Deficiency
of either enzyme leads to an accumulation of keratan sulfate and bony
abnormalities of the head, chest, hands, knees and spine may occur as a
result of this metabolic defect, with preservation of intellect.  The
skeletal abnormalities in MPS IV-B are usually milder than in MPS IV-A.

Symptoms

Developmental abnormalities occurring in Morquio Syndrome may be detected as
early as 18 months to 2 years of age.  The skeletal abnormalities are milder
in Morquio Syndrome A than in Morquio Syndrome B.  These may include an
enlarged head, a broad mouth, prominent cheekbones, an unusually small nose,
widely spaced and thinly enameled teeth, and widely separated eyes with
corneal clouding.  Later, patients tend to develop abnormally short necks,
short barrel chests, disproportionately long arms, enlarged and possibly
hyperextensible wrists, stubby hands and "knock knees".  Together with the
misaligned knees and knobby joints, the child may be "pigeon-toed", causing a
wobbly gait.  The joint laxity and bony abnormalities of the spine can result
in life-threatening spinal cord compression.  Surgery to stabilize the upper
cervical spine, usually by spinal fusion, can be lifesaving.

There may also be enlargement of the liver, curvature of the spine
(thoracic kyphoscoliosis), flow of blood from the aorta back into the left
ventricle of the heart (aortic regurgitation), and hearing loss.

Causes

Morquio Disease is an autosomal recessive hereditary disorder in which a
deficiency of galactosamine 6 sulfatase in type A of the disorder, and a
deficiency of beta-galactosidase in type B, leads to an accumulation of
keratan sulfate in the urine.  (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

Morquio Syndrome affects males as often as females.  The disorder occurs in
less than 1 in 100,000 live births except in the French-Canadian population
where it is known to be the most common type of mucopolysaccharidoses.

Related Disorders

There are many types of Mucopolysaccharidosis.  Information about each of
these types of MPS can be located in the Rare Disease Database.  (For more
information, choose "MPS Disorders" as your search term in the Rare Disease
Database.)

DiFerrante syndrome (mucopolysaccharidosis VIII) is a disorder described
in a single patient with clinical and biochemical features of Morquio and
Sanfilippo syndromes.  The disorder had been reported to be due to a
deficiency of glucosamine-6-sulfate sulfatase.  Subsequently, this disorder
was called MPS VIII (DiFerrante syndrome).  Dr. DiFerrante later found that
the enzyme was normal in his patient, and the disorder had been misdiagnosed.
Therefore, DiFerrante syndrome is not a valid medical disorder.

The Mucolipidoses are a family of similar disorders, producing symptoms
very much like those of the Mucopolysaccharidoses.

I-cell disease, or Mucolipidosis Type II, resembles Hurler syndrome and
the two disorders are very difficult to distinguish.  I-cell disease has
similar physical and mental deterioration as MPS I, but usually occurs
earlier and is more severe.  I-cell diseases is characterized by diffused
deficiency of lysosomal enzymes with the cell and is not associated with
excretion of mucopolysaccharides in the urine.

Pseudo-Hurler Polydystrophy (Mucolipidosis III) is also transmitted by
autosomal inheritance, but it is characterized by a deficiency of multiple
lysosomal enzymes needed to break down mucopolysaccharides.  ML III affects
males more often than females, and can be identified by such symptoms as
claw-like hands, somewhat coarse facial features, dwarfism and pain in the
hands.  Intelligence tends to be normal in most patients, but mild mental
retardation is sometimes present.

Ganglioside Sialidase Deficiency (Mucolipidosis IV) is a disorder of
unknown cause characterized by early clouding of the cornea, mild to moderate
mental retardation and enlargement of spleen and liver.

(For more information on the Mucolipidoses, choose "ML Disorder" as your
search term in the Rare Disease Database.)

Therapies:  Standard

Treatment of Morquio Syndrome is symptomatic and supportive.  Physical
therapy and special educational services may be helpful.  Genetic counseling
may be helpful to the parents of patients with Morquio Syndrome.  Prenatal
diagnosis is now possible for this disorder.

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 Morquio Syndrome are now under study.
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 may someday be made
available to people with genetic disorders such as Morquio Syndrome.

The Mayo Clinic is investigating the use of Alpha Interferon as a
treatment for Morquio Syndrome.  For more information, physicians can
contact:

     Morie A. Gertz, M.D.
     Dept. of Hematology & Internal Medicine
     Mayo Clinic
     Rochester, MN  55905
     [phone]

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 Morquio Syndrome, please contact:

     National Organization for Rare Disorders (NORD)
     P.O. Box 8923
     New Fairfield, CT  06812-1783
     [phone]

     MPS (Mucopolysaccharidoses) Research Funding Center, Inc.
     1215 Maxfield Road
     Hartland, MI  48029
     [phone]

     National MPS Society
     17 Kramer Street
     Hicksville, NY  11801
     [phone]

     National Digestive Diseases Information Clearinghouse
     Box NDDIC
     Bethesda, MD  20892
     [phone]

     Society of Mucopolysaccharide Diseases, Inc.
     382 Parkway Blvd.
     Flin Flon, Manitoba, Canada R8A OK4

     Society of MPS Diseases
     30 Westwood Drive
     Little Chalfont, Bucks, England

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

     March of Dimes Birth Defects Foundation
     1275 Mamaroneck Avenue
     White Plains, NY  10605
     [phone]

     Alliance of Genetic Support Groups
     35 Wisconsin Circle, Suite 440
     Chevy Chase, MD  20815
     (800) 336-GENE
     [phone]

References

MPS Society Brochure.

BIRTH DEFECTS COMPENDIUM, 2nd ed.:  Daniel Bergsma, ed:  March of Dimes,
1979.  P. 732.

MENDELIAN INHERITANCE IN MAN, 6th ed.:  Victor A McKusick; Johns Hopkins
University Press, 1983.  Pp. 840-841.