Morquio syndrome is a disease of metabolism in which the body is missing or does not have enough of a substance needed to break down long chains of sugar molecules. These chains of molecules are called glycosaminoglycans (formerly called mucopolysaccharides).
The syndrome belongs to a group of diseases called mucopolysaccharidoses (MPS). Specifically, it is known as MPS IV.
- MPS I H (Hurler syndrome)
- MPS II, Hunter syndrome
- MPS III (Sanfilippo syndrome)
- MPS I S (Scheie syndrome)
Mucopolysaccharidosis type IVA; Galactosamine-6-sulfatase deficiency; Mucopolysaccharidosis type IVB; Beta galactosidase deficiency; MPS IV
Morquio syndrome is an inherited condition, which means it is passed down through families. If both parents carry a nonworking copy of a gene related to this condition, each of their children has a 25% (1 in 4) chance of developing the disease. This is called an autosomal recessive trait.
There are 2 forms of Morquio syndrome: Type A and Type B.
- People with Type A do not have a substance (enzyme) called galactosamine-6-sulfatase.
- People with Type B do not produce enough of an enzyme called beta-galactosidase.
The body needs these enzymes to break down a long strand of sugar molecules called the keratan sulfate sugar chain. In both types, abnormally large amounts of glycosaminoglycans build up in the body. This can damage organs.
Symptoms usually start between ages 1 and 3. They include:
- Abnormal development of bones, including the spine
- Bell-shaped chest with ribs flared out at the bottom
- Coarse facial features
- Hypermobile joints
- Large head
- Short stature with a particularly short trunk
- Widely spaced teeth
Exams and Tests
The health care provider will perform a physical examination. Examination and testing may reveal:
- Abnormal curvature of the spine
- Cloudy cornea
- Heart murmur
- Hernia in the groin
- Enlarged liver
- Loss of nerve function below the neck
- Short stature (especially short trunk)
Urine tests are usually done first. These tests may show extra mucopolysaccharides, but they can't determine the specific form of MPS.
Other tests may include:
- Blood culture
- Genetic testing
- Hearing test
- Slit-lamp eye exam
- Skin fibroblast culture
- X-rays of the long bones, ribs, and spine
People with Morquio syndrome should have MRI of the lower skull and upper neck to determine if their upper vertebrae are underdeveloped.
The U.S. Food and Drug Administration has approved a medicine for Morquio syndrome type A, called elosulfase alfa (Vimizim). It is given through a vein (IV, intravenously). Talk to your provider for more information.
Symptoms are treated as they occur. A spinal fusion may prevent permanent spinal cord injury in people whose neck bones are underdeveloped.
For more information and support, contact one of the following organizations:
- The National MPS Society -- www.mpssociety.org
- Canadian Society for MPS and Related Diseases -- www.mpssociety.ca
- Society for MPS Diseases -- www.mpssociety.co.uk
Cognitive function (ability to think clearly) is usually normal in people with Morquio syndrome.
Bone problems can lead to significant complications. For example, the small bones at the top of the neck may slip and damage the spinal cord, causing paralysis. Surgery to correct such problems should be done if possible.
Heart problems may lead to death.
These complications may occur:
- Breathing problems
- Heart failure
- Spinal cord damage and possible paralysis
- Vision problems
- Walking problems related to abnormal curvature of the spine and other bone problems
When to Contact a Medical Professional
Call your provider if symptoms of Morquio syndrome occur.
Genetic counseling is recommended for couples who want to have children and who have a family history of Morquio syndrome. Counseling is also recommended for families who have a child with Morquio syndrome to help them understand the condition and possible treatments. Prenatal testing is available.
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Wraith JE. Mucopolysaccharidoses and oligosaccharidoses. In: Saudubray J-M, van den Berghe G, Walter JH, eds. Inborn Metabolic Diseases: Diagnosis and Treatment. 5th ed. New York, NY: Springer; 2012:chap 40.
Reviewed By: Chad Haldeman-Englert, MD, FACMG, Wake Forest School of Medicine, Department of Pediatrics, Section on Medical Genetics, Winston-Salem, NC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.