Mucopolysaccharidosis Type IVA

Mucopolysaccharidosis type IVA or Morquio syndrome A is a lysosomal storage disorder characterized by skeletal dysplasia due to excessive storage of keratan sulfate. Affected individuals usually present with unusual skeletal features including short trunk dwarfism, odontoid hypoplasia, pectus carinatum, kyphosis, gibbus, scoliosis, genu valgus, coxa valga, and flaring of the lower ribs. Hypermobile joints and an abnormal gait with a tendency to fall may also be presenting features. Unlike other mucopolysaccharidoses (MPS) intelligence is often preserved. Odontoid hypoplasia is the most serious skeletal finding because, in combination with ligamentous laxity and mucopolysaccharide deposition, it may result in atlantoaxial subluxation, cervical myelopathy or even death. Other possible features include pulmonary compromise, valvular heart disease, hearing loss, hepatomegaly, fine corneal clouding, and widely spaced teeth with abnormally thin enamel with increased risk of caries formation. Patients may also have coarse facial features, although this is usually milder than that seen in MPSI or MPSII. Patients appear healthy at birth with initial symptoms usually presenting by the age of 3 years, at which time the patient is usually evaluated due to the unusual skeletal features. Morquio syndrome A patients exhibit a wide spectrum of clinical symptoms and more mildly affected patients may have a normal quality of life and mild bone and visceral organ involvement. The incidence of Morquio syndrome A has been estimated to be from 1 in 76,000 in Northern Ireland to 1 in 450,000 in Portugal.

Tests Available

Forms and Documents

Test Details

  • Confirmation of a biochemical diagnosis
  • Carrier testing
  • Prenatal diagnosis in at risk pregnancy


4 weeks
2-5 mL Blood - Lavender Top Tube
Buccal Swabs

*Reporting times are typical, but could be extended in situations outside GeneDx's reasonable control.


  • 277.5 Mucopolysaccharidosis Gargoylism Hunter's syndrome Hurler's syndrome Lipochondrodystrophy Maroteaux-Lamy syndrome Morquio-Brailsford disease Osteochondrodystrophy Sanfilippo's syndrome Scheie's syndrome
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**The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.


  1. Tomatsu et al., (2005) Hum Mutat 26:500-512.
  2. Tomatsu et al., (2004) Hum Mutat 24:187.