Morquio syndrome

  • Definition
  • Alternative Names
    • Mucopolysaccharidosis type IVA; Galactosamine-6-sulfatase deficiency; Mucopolysaccharidosis type IVB; Beta galactosidase deficiency; MPS IV

  • Causes
    • 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
    • Symptoms usually start between ages 1 and 3. They include:

  • Exams and Tests
    • The health care provider will perform a physical examination. Examination and testing may reveal:

      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:

      People with Morquio syndrome should have MRI of the lower skull and upper neck to determine if their upper vertebrae are underdeveloped.

  • Treatment
    • 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.

  • Support Groups
  • Outlook (Prognosis)
    • 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.

  • Possible Complications
    • 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.

  • Prevention
    • 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.

  • References
    • National Institute of Neurological Disorders and Stroke. Mucolipidoses Fact Sheet. Office of Communications and Public Liaison. Bethesda, MD; Publication No. 03-5115. February 13, 2007.

      Pyeritz RE. Inherited diseases of connective tissue. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 260.

      Spranger J. Mucopolysaccharidoses. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 82.

      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.