Morquio Syndrome

What does the name mean?

Morquio Syndrome is another name for mucopolysaccharidosis IV (MPS IV); it was first described by Luis Morquio in 1919 (4).

How common is Morquio syndrome?

The frequency of Morquio syndrome is 1 in 640,000 births (7).

Is Morquio syndrome inherited?

Morquio syndrome follows an autosomal recessive inheritance pattern (9).

What causes Morquio syndrome?

A mutation is the GALNS gene, which encodes for N-acetyl galactosamine-6-sulfatase, causes Morquio, type A (4). Type B is caused by mutations of the GLB1 gene, which encodes for β-galactosidase (4). Both enzymes, however, are responsible for keratan sulfate degradation. In type A, the activity of the sulfatase was found to be less than 1% (6). Due to the enzymes’ ineffectiveness, mucopolysaccharides aggregate within intracellular lysosomes. Mucopolysaccharides are long, unbranched chains of repeating saccharide, or sugar, units. They are important components of the body’s connective tissues and are often times covalently linked to proteins. In Morquio Syndrome, the lysosomal enzymes that are responsible for breaking down mucopolysaccharides are ineffective. As a result, the long sugar molecules begin to collect in the body’s cells and connective tissues. The accumulation ultimately causes cellular damage that manifests as skeletal malformations.

• What are the physical characteristics of Morquio Syndrome?
• How is the diagnosis made?
• Problems in the musculoskeletal system
• Problems elsewhere in the body
• What are things to watch out for?
• References