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Mucopolysaccharidosis type IV


Other Names:
MPS4; MPSIV; Mucopolysaccharidosis type 4; MPS4; MPSIV; Mucopolysaccharidosis type 4; Morquio disease See More
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Subtypes:
This disease is grouped under:
Mucopolysaccharidosis type IV (MPS IV), also known as Morquio syndrome, is a rare metabolic condition in which the body is unable to break down long chains of sugar molecules called glycosaminoglycans. As a result, toxic levels of these sugars accumulate in cell structures called lysosomes, leading to the various signs and symptoms associated with the condition. Affected people generally develop features of MPS IV between the ages of 1 and 3. These signs and symptoms may include abnormalities of the skeleton, eyes, heart and respiratory system. There are two forms of MPS IV: Both forms are inherited in an autosomal recessive manner. Treatment is based on the signs and symptoms present in each person.[1][2][3]
Last updated: 7/30/2017
People affected by mucopolysaccharidosis type IV (MPS IV) often develop signs and symptoms of the condition in early childhood. The condition is considered progressive; however, the rate at which symptoms worsen varies significantly among affected people. All people affected by MPS IV develop skeletal problems such as scoliosis, knock-knees, short stature, pectus carinatum and variety of other abnormalities of the ribs, chest, spine, hips, and wrists.[1][4] Another common feature of MPS IV is an underdeveloped odontoid process (a peg-like bone in the neck that helps stabilize the cervical vertebrae). This can misalign, compress and damage the spinal cord, leading to paralysis or even death.[1]

Other features of the condition include:[1][5]
  • Coarse facial features
  • Hypermobile joints
  • Corneal clouding and vision loss
  • Heart valve abnormalities
  • Respiratory complications, including airway obstruction, sleep apnea and restrictive lung disease
  • Widely-spaced, discolored teeth with thin enamel
  • Mild to moderate hearing loss
  • Mild hepatomegaly

Last updated: 7/23/2017

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Abnormality of epiphysis morphology
Abnormal shape of end part of bone
0005930
Abnormality of the metaphysis
Abnormality of the wide portion of a long bone
0000944
Abnormality of the ribs
Rib abnormalities
0000772
Corneal opacity 0007957
Delayed skeletal maturation
Delayed bone maturation
Delayed skeletal development
[ more ] 		0002750
Gait disturbance
Abnormal gait
Abnormal walk
Impaired gait
[ more ] 		0001288
Genu valgum
Knock knees
0002857
Hearing impairment
Deafness
Hearing defect
[ more ] 		0000365
Joint hyperflexibility
Joints move beyond expected range of motion
0005692
Mucopolysacchariduria 0008155
Pectus carinatum
Pigeon chest
0000768
Reduced bone mineral density
Low solidness and mass of the bones
0004349
Short neck
Decreased length of neck
0000470
Short stature
Decreased body height
Small stature
[ more ] 		0004322
Short thorax
Shorter than typical length between neck and abdomen
0010306
30%-79% of people have these symptoms
Abnormal heart valve morphology 0001654
Anteverted nares
Nasal tip, upturned
Upturned nasal tip
Upturned nose
Upturned nostrils
[ more ] 		0000463
Carious teeth
Dental cavities
Tooth cavities
Tooth decay
[ more ] 		0000670
Coarse facial features
Coarse facial appearance
0000280
Coxa valga 0002673
Grayish enamel
Gray colored tooth enamel
Greyish enamel
[ more ] 		0000683
Hernia 0100790
Hyperlordosis
Prominent swayback
0003307
Joint dislocation
Joint dislocations
Recurrent joint dislocations
[ more ] 		0001373
Kyphosis
Hunched back
Round back
[ more ] 		0002808
Platyspondyly
Flattened vertebrae
0000926
Scoliosis 0002650
Spinal canal stenosis
Narrow spinal canal
0003416
Wide mouth
Broad mouth
Large mouth
[ more ] 		0000154
5%-29% of people have these symptoms
Cognitive impairment
Abnormality of cognition
Cognitive abnormality
Cognitive defects
Cognitive deficits
Intellectual impairment
Mental impairment
[ more ] 		0100543
Macrocephaly
Increased size of skull
Large head
Large head circumference
[ more ] 		0000256
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Last updated: 7/1/2020
There are two forms of mucopolysaccharidosis type IV (MPS IV): type A and type B. Type A is caused by changes (mutations) in the GALNS gene and type B is caused by mutations in the GLB1 gene. Both of these genes encode enzymes that help the body breakdown large sugar molecules called glycosaminoglycans (GAGs). If mutations reduce or eliminate the amount of these enzymes functioning in the body, GAGs accumulate in specialized cell structures called lysosomes (compartments in the cell that break down and recycle different types of molecules). This buildup of GAGs is toxic to various tissues in the body and leads to the signs and symptoms associated with the condition.[6][2]
Last updated: 7/24/2017

Mucopolysaccharidosis type IV is inherited in an autosomal recessive manner.[1] This means that to be affected, a person must have a mutation in both copies of the responsible gene in each cell. Affected people inherit one mutated copy of the gene from each parent, who is referred to as a carrier. Carriers of an autosomal recessive condition typically do not have any signs or symptoms (they are unaffected). When 2 carriers of an autosomal recessive condition have children, each child has a:

  • 25% (1 in 4) chance to be affected
  • 50% (1 in 2) chance to be an unaffected carrier like each parent
  • 25% chance to be unaffected and not be a carrier
Last updated: 7/25/2017
A diagnosis of mucopolysaccharidosis type IV is often suspected based on the presence of characteristic signs and symptoms. Additional testing can then be ordered to confirm the diagnosis, determine the severity of the condition and rule out other conditions that can be associated with similar features. These tests may include:[1][3]
  • X-rays
  • Specialized urine and blood tests
  • Eye exam
  • Skin fibroblast culture
  • Genetic testing to identify mutations in the GALNS or GLB1 genes
Last updated: 7/28/2017

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Financial Resources

  • National Organization for Rare Disorders (NORD) has Disease-Specific Assistance Programs designed to help patients with out-of-pocket costs such as monthly insurance premiums or deductibles. In addition, some programs may provide financial assistance for additional expenses related to a patient's diagnosis such as travel to see a specialist.

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • Genetics Home Reference (GHR) contains information on Mucopolysaccharidosis type IV. This website is maintained by the National Library of Medicine.
  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
  • The National Institute of Neurological Disorders and Stroke (NINDS) (NINDS) collects and disseminates research information related to neurological disorders. Click on the link to view information on this topic.
  • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.

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  1. Debra S Regier, MD, PhD, Matthew Oetgen, MD, and Pranoot Tanpaiboon, MD. Mucopolysaccharidosis Type IVA. GeneReviews. March 2016; https://www.ncbi.nlm.nih.gov/books/NBK148668.
  2. Kazuki Sawamoto, PhD, MS. Morquio Syndrome (Mucopolysaccharidosis Type IV). Medscape Reference. July 2017; http://emedicine.medscape.com/article/947254-overview.
  3. Mucopolysaccharidosis IV. National Organization for Rare Disorders. 2016; https://rarediseases.org/rare-diseases/morquio-syndrome/.
  4. Di Cesare A, Di Cagno A, Moffa S, Teresa P, Luca I, Giombini A. A description of skeletal manifestation in adult case of morquio syndrome: radiographic and MRI appearance. Case Rep Med. 2012; 2012:324596.
  5. Robert Wynn, MD, MRCP, FRCPath. Mucopolysaccharidoses: Clinical features and diagnosis. UpToDate. June 2017; Accessed 7/24/2017.
  6. Mucopolysaccharidosis type IV. Genetics Home Reference. July 2010; https://ghr.nlm.nih.gov/condition/mucopolysaccharidosis-type-iv.