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Disease Profile

Mucopolysaccharidosis type IVA

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

1-5 / 10 000

US Estimated

Europe Estimated

Age of onset






Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

MPS IVA; MPS 4A; Morquio A disease;


Congenital and Genetic Diseases; Eye diseases; Metabolic disorders;


Mucopolysaccharidosis type IVA (MPS IVA, also called Morquio syndrome, type A) is a metabolic condition that primarily affects the skeleton. The severity, age of onset, and associated symptoms vary significantly from person to person and range from a severe and rapidly progressive, early-onset form to a slowly progressive, later-onset form. The severe form is usually diagnosed between ages 1 and 3, while the milder form may not become evident until late childhood or adolescence. Signs and symptoms include various skeletal abnormalities such as short stature, knock knees, pectus carinatum, and malformations of the spine, hips and wrists. Affected people may also experience involvement of other organ systems such as respiratory problems, valvular heart disease, hearing impairment, corneal clouding, dental abnormalities, hepatomegaly, and spinal cord compression.[1][2] MPS IVA is caused by changes (mutations) in the GALNS gene and is inherited in an autosomal recessive manner.[3] Treatment is based on the signs and symptoms present in each person.[1]


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.

Medical Terms Other Names
Learn More:
Percent of people who have these symptoms is not available through HPO
Abnormal heart valve morphology
Autosomal recessive inheritance
Carious teeth
Dental cavities
Tooth cavities
Tooth decay

[ more ]

Cervical myelopathy
Cervical subluxation
Chondroitin sulfate excretion in urine
Coarse facial features
Coarse facial appearance
Constricted iliac wings
Coxa valga
Disproportionate short-trunk short stature
Disproportionate short-trunked dwarfism
Disproportionate short-trunked short stature
Short-trunked dwarfism

[ more ]

Epiphyseal deformities of tubular bones
Flaring of rib cage
Genu valgum
Knock knees
Grayish enamel
Gray colored tooth enamel
Greyish enamel

[ more ]

Hearing impairment
Hearing defect

[ more ]

Enlarged liver
Prominent swayback
Hypoplasia of the odontoid process
Inguinal hernia
Joint laxity
Joint instability
Lax joints

[ more ]

Juvenile onset
Signs and symptoms begin before 15 years of age
Keratan sulfate excretion in urine
Hunched back
Round back

[ more ]

Large elbow
Mandibular prognathia
Big lower jaw
Increased projection of lower jaw
Increased size of lower jaw
Large lower jaw
Prominent chin
Prominent lower jaw

[ more ]

Metaphyseal widening
Broad wide portion of long bone
Opacification of the corneal stroma
Ovoid vertebral bodies
Flattened vertebrae
Pointed proximal second through fifth metacarpals
Prominent sternum
Recurrent upper respiratory tract infections
Recurrent colds
Restrictive ventilatory defect
Stiff lung or chest wall causing decreased lung volume
Ulnar deviation of the wrist
Wide mouth
Broad mouth
Large mouth

[ more ]

Widely spaced teeth
Wide-spaced teeth
Widely-spaced teeth

[ more ]



Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.


    The resources below provide information about treatment options for this condition. If you have questions about which treatment is right for you, talk to your healthcare professional.

    Management Guidelines

    • Project OrphanAnesthesia is a project whose aim is to create peer-reviewed, readily accessible guidelines for patients with rare diseases and for the anesthesiologists caring for them. The project is a collaborative effort of the German Society of Anesthesiology and Intensive Care, Orphanet, the European Society of Pediatric Anesthesia, anesthetists and rare disease experts with the aim to contribute to patient safety.

      FDA-Approved Treatments

      The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.


      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

        Learn more

        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

        • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
        • Genetics Home Reference (GHR) contains information on Mucopolysaccharidosis type IVA. This website is maintained by the National Library of Medicine.
        • 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

          • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
          • 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.
          • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
          • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
          • PubMed is a searchable database of medical literature and lists journal articles that discuss Mucopolysaccharidosis type IVA. Click on the link to view a sample search on this topic.


            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. Mucopolysaccharidosis type IV. Genetics Home Reference. July 2010; https://ghr.nlm.nih.gov/condition/mucopolysaccharidosis-type-iv.
            3. MUCOPOLYSACCHARIDOSIS, TYPE IVA. OMIM. September 2015; https://www.omim.org/entry/253000.