Sly Syndrome

What is Sly Syndrome?

Sly Syndrome is a type of mucopolysaccharide disorder named for William Sly, who originally described the disorder in 1972. It is a rare genetic disorder caused by the deficiency of a lysosomal enzyme called beta-gluconuronidase which is essential in breaking down used mucopolysaccharides (specifically, heparan sulfate, chondroitin 4, 6-sulfates, and dermatan sulfate). The build up of these mucopolysaccharides in the cells of the body cause progressive damage. As more and more damage occurs, signs and symptoms in the child begin to appear.

Signs and Symptoms

Babies born with this disorder may show little sign of this disease and clinical features can vary from person to person depending on the severity of the disease. However, most patients exhibit the following features:

  • Short stature due to growth retardation
  • Changes in bones (skeletal abnormalities)
  • Mental retardation
  • Coarsening of facial features
  • Clouding of the cornea
  • Enlargement of liver and spleen

How Does One Inherit This Disorder?

Sly Syndrome is a caused by a recessive gene. This means that if an adult carrying the abnormal gene has a child with another adult with the same abnormal gene, that couple has a one in four chance of having a child with this disorder. The siblings to these children also have a two in three chance of being carriers of these genes.

Incidence of Sly Syndrome

Sly Syndrome is a rare genetic disorder and it is estimated to occur in less than 1 in 250,000 births.

Treatments and Cures

There is currently NO cure for Sly Syndrome or any of the other mucopolysaccharide disorders. Bone marrow transplants and enzyme replacement therapy have been used in other mucopolysaccharide disorders and in animal models with some success however, there is little experience with its effectiveness with Sly Syndrome.

Sly Syndrome is also known as:

  • Beta-Gluconuronidase Deficiency
  • GUSB Deficiency

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