Mucopolysaccharidosis type IV
MPS IV; Morquio syndrome; Mucopolysaccharidosis type IVA; MPS IVA; Galactosamine-6-sulfatase deficiency; Mucopolysaccharidosis type IVB; MPS IVB; Beta galactosidase deficiency; Lysosomal storage disease - mucopolysaccharidosis type IVMucopolysaccharidosis type IV (MPS IV) is a rare disease in which the body is missing or does not have enough of an enzyme needed to break down long chains of sugar molecules. These chains of molecules are called glycosaminoglycans (formerly called mucopolysaccharides). As a result, the molecules build up in different parts of the body and cause various health problems.
Enzyme
Enzymes are complex proteins that cause a specific chemical change. For example, they can help break down the foods we eat so the body can use them....
Read Article Now Book Mark ArticleThe condition belongs to a group of diseases called mucopolysaccharidoses (MPSs). MPS IV is also known as Morquio syndrome.
Mucopolysaccharidoses
Mucopolysaccharidoses (MPSs) are a group of rare diseases in which the body is missing or does not have enough of an enzyme needed to break down long...
Read Article Now Book Mark ArticleThere are several other types of MPSs, including:
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MPS I (Hurler syndrome; Hurler-Scheie syndrome; Scheie syndrome)
MPS I
Mucopolysaccharidosis type I (MPS I) is a rare disease in which the body is missing or does not have enough of an enzyme needed to break down long ch...
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MPS II (Hunter syndrome)
MPS II
Mucopolysaccharidosis type II (MPS II) is a rare disease in which the body is missing or does not have enough of an enzyme needed to break down long ...
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MPS III (Sanfilippo syndrome)
MPS III
Mucopolysaccharidosis type III (MPS III) is a rare disease in which the body is missing or does not have enough of certain enzymes needed to break do...
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Causes
MPS IV is an inherited disorder. This means it is typically 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.
Autosomal recessive
Autosomal recessive is one of several ways that a genetic trait, disorder, or disease can be passed down through families. An autosomal recessive dis...
Read Article Now Book Mark ArticleThere are two forms of MPS IV: type A and type B.
- Type A is caused by a defect in the GALNS gene. People with type A do not have an enzyme called N-acetylgalactosamine-6-sulfatase.
- Type B is caused by a defect in the GLB1 gene. People with type B do not produce enough of an enzyme called beta-galactosidase.
The body needs these enzymes to break down long strands of sugar molecules called keratan sulfate. In both types, abnormally large amounts of glycosaminoglycans build up in the body. This can damage bodily organs.
Symptoms
Symptoms usually start between ages 1 and 3 years. They include:
- Abnormal development of bones, including the spine
- Bell-shaped chest with ribs flared out at the bottom
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Cloudy cornea
Cloudy cornea
A cloudy cornea is a loss of transparency of the cornea.
Read Article Now Book Mark Article - Coarse facial features
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Enlarged liver
Enlarged liver
Enlarged liver refers to swelling of the liver beyond its normal size. Hepatomegaly is another word to describe this problem. If both the liver and ...
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Heart murmur
Heart murmur
A heart murmur is a blowing, whooshing, or rasping sound heard during a heartbeat. The sound is caused by turbulent (rough) blood flow through the h...
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Hernia in the groin
Hernia in the groin
A hernia is a sac formed by the lining of the abdominal cavity (peritoneum). The sac comes through a hole or weak area in the strong layer of the be...
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Hypermobile joints
Hypermobile joints
Hypermobile joints are joints that move beyond the normal range with little effort. Joints most commonly affected are the elbows, wrists, fingers, a...
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Knock-knees
Knock-knees
Knock knees are condition in which the knees touch, but the ankles do not touch. The legs turn inward.
Read Article Now Book Mark Article - Large head
- Loss of nerve function below the neck
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Short stature with a particularly short trunk
Short stature
A child who has short stature is much shorter than children who are the same age and sex. Your health care provider will go over your child's growth ...
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Widely spaced teeth
Widely spaced teeth
Widely spaced teeth can be a temporary condition related to normal growth and development of adult teeth. Wide spacing can also occur as a result of...
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Exams and Tests
Your health care provider will perform a physical exam that may find:
- Abnormal curvature of the spine
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Cloudy cornea
Cloudy cornea
A cloudy cornea is a loss of transparency of the cornea.
Read Article Now Book Mark Article - Heart murmur
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Hernia in the groin
Hernia in the groin
A hernia is a sac formed by the lining of the abdominal cavity (peritoneum). The sac comes through a hole or weak area in the strong layer of the be...
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Enlarged liver
Enlarged liver
Enlarged liver refers to swelling of the liver beyond its normal size. Hepatomegaly is another word to describe this problem. If both the liver and ...
Read Article Now Book Mark Article - 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 enzyme levels
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Echocardiogram
Echocardiogram
An echocardiogram is a test that uses sound waves to create pictures of the heart. The picture and information it produces is more detailed than a s...
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Hearing test
Hearing test
An audiometry exam tests your ability to hear sounds. Sounds vary, based on their loudness (intensity) and the speed of sound wave vibrations (tone)...
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Slit-lamp eye exam
Slit-lamp
The slit-lamp examination looks at structures that are at the front of the eye.
Read Article Now Book Mark Article - Skin fibroblast culture
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X-rays of the long bones, ribs, and spine
X-rays
X-rays are a type of electromagnetic radiation, just like visible light. An x-ray machine sends individual x-ray waves through the body. The images...
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MRI of the lower skull and upper neck
MRI
A magnetic resonance imaging (MRI) scan is an imaging test that uses powerful magnets and radio waves to create pictures of the body. It does not us...
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Treatment
For type A, the medicine called elosulfase alfa (Vimizim), which replaces the missing enzyme, may be tried. It is given through a vein (IV, intravenously). Talk to your provider for more information.
Enzyme replacement therapy is not available for type B.
For both types, symptoms are treated as they occur. A spinal fusion may prevent permanent spinal cord injury in people whose neck bones are underdeveloped.
Support Groups
More information and support for people with MPS IV and their families can be found at:
- National MPS Society -- mpssociety.org/
- National Organization for Rare Disorders -- rarediseases.org/gard-rare-disease/mucopolysaccharidosis-type-iv/
- NIH Genetic and Rare Diseases Information Center -- rarediseases.info.nih.gov/diseases/12562/mucopolysaccharidosis-type-iv
Outlook (Prognosis)
Cognitive function (ability to think clearly) is usually normal in people with MPS IV.
Bone problems can lead to major health problems. 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
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Heart failure
Heart failure
Heart failure is a condition in which the heart is no longer able to pump oxygen-rich blood to the rest of the body efficiently. This causes symptom...
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- Vision problems
- Walking problems related to abnormal curvature of the spine and other bone problems
When to Contact a Medical Professional
Contact your provider if symptoms of MPS IV occur.
Prevention
Genetic counseling is recommended for couples who want to have children and who have a family history of MPS IV. Prenatal testing is available.
Genetic counseling
Genetics is the study of heredity, the process of a parent passing certain genes on to their children. A person's appearance, such as height, hair co...
Read Article Now Book Mark ArticleReferences
Pyeritz RE. Inherited diseases of connective tissue. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 239.
Spranger JW. Mucopolysaccharidoses. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 107.
Turnpenny PD, Ellard S, Cleaver R. Inborn errors of metabolism. In: Turnpenny PD, Ellard S, Cleaver R, eds. Emery's Elements of Medical Genetics and Genomics. 16th ed. Philadelphia, PA: Elsevier; 2022:chap 18.
Review Date: 4/24/2023
Reviewed By: Anna C. Edens Hurst, MD, MS, Associate Professor in Medical Genetics, The University of Alabama at Birmingham, Birmingham, AL. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.