Morquio Syndrome: Causes and Symptoms

What is Morquio syndrome?

Morquio syndrome (also called mucopolysaccharidoses, type IV or MPSIV) is a genetic condition in which the body creates too little N-acetylgalactosamine 6-sulfatase or B-galactosidase enzyme. These enzymes help break down certain types of sugar in the body. Without enough of either enzyme, the body cannot break down certain sugars.

There are 2 forms of Morquio syndrome: early and slowly progressive forms. The difference between the two forms depends on when symptoms first begin and how quickly they progress.

What are the symptoms of Morquio syndrome?

• Progressive skeletal problems (conditions that affect the bones that get worse over time)
  • Short stature (short height)
  • Shortened neck
  • Significant spinal cord deformities (physical differences that affect the shape, size and length of the spinal cord)
• Clouded cornea (the clear, protective outer layer of the eyes)
• Prominent (larger or more noticeable) facial features
• Enlarged liver (liver that is larger than usual)

What causes Morquio syndrome?

Morquio syndrome is caused by changes in the GALNS gene. Genes are the instructions that tell our bodies how to develop and function. The job of the GALNS gene is to create the N-acetylgalactosamine 6-sulfatase or B-galactosidase enzyme.

People with certain misspellings in the GALNS gene create too little or no N-acetylgalactosamine 6-sulfatase or B-galactosidase enzyme.

Morquio syndrome is inherited (passed down from parent to child) in an autosomal recessive pattern (when a child inherits a mutated, or changed, gene from each parent who carries the gene for the condition but does not have the condition itself). Our genes come in pairs. We get one copy from our biological mother and the other from our biological father. In Morquio syndrome, both copies of the GALNS gene have a misspelling or mutation that causes it to create less or no enzyme.

Rev. 6/2022. Mass General for Children and Massachusetts General Hospital do not endorse any of the brands listed on this handout. This handout is intended to provide health information so you can be better informed. It is not a substitute for medical advice and should not be used to treat any medical conditions.