Mucopolysaccharidosis type 4A

Mucopolysaccharidosis type 4A (MPS 4A), also known as Morquio A syndrome or Morquio disease type A, is a rare inherited metabolic disorder. It belongs to a group of conditions called lysosomal storage diseases. In this condition, the body cannot produce enough of an enzyme called N-acetylgalactosamine-6-sulfatase (GALNS). This enzyme is needed to break down certain complex sugars called glycosaminoglycans (GAGs), specifically keratan sulfate and chondroitin-6-sulfate. When these sugars build up in the body's cells, they cause progressive damage, especially to bones, cartilage, and connective tissues. The hallmark features of Morquio A syndrome include short stature, skeletal abnormalities, and joint problems. Children often appear normal at birth but begin showing signs in early childhood. Common problems include a short trunk, knock-knees, a prominent chest (pectus carinatum), spinal abnormalities, and loose joints. The neck can be particularly affected, with instability of the upper spine that can be dangerous. Unlike some other types of MPS, intelligence is usually normal in Morquio A syndrome. However, the disease can also affect the heart, eyes, ears, and breathing. Treatment options have expanded in recent years. An enzyme replacement therapy called elosulfase alfa (Vimizim) was approved by the FDA in 2014 and helps slow the progression of the disease. Supportive care including orthopedic surgeries, physical therapy, and monitoring of the heart and airways remain essential parts of management. Hematopoietic stem cell transplant is being explored but is not yet standard treatment for this type of MPS.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

Bring these to your next appointment

• Q1.How severe is my child's form of Morquio A, and what can we expect over time?,Is the cervical spine (neck) stable, and when should we consider spinal surgery?,Should we start enzyme replacement therapy (Vimizim), and what are the benefits and risks?,How often do we need imaging of the spine, heart, and other organs?,What activities should we avoid to protect the neck and spine?,Are there any clinical trials for new treatments that we should consider?,What precautions are needed if my child ever needs surgery or anesthesia?

Common questions about Mucopolysaccharidosis type 4A