Snyder-Robinson Syndrome

What is Snyder-Robinson syndrome?

Snyder-Robinson syndrome is an inherited condition that is characterized by intellectual disability, muscle and bone abnormalities, and other problems with development. It only occurs in males. Affected individuals have delayed development that begins in early childhood. Speech difficulties are common. Low muscle tone (hypotonia) and muscle mass leads to difficulty walking and an unsteady gait. Other features include thinning of the bones (osteoporosis), an abnormal curvature of the spine (kyphoscoliosis), and unusual facial features including a prominent lower lip, cleft palate, and facial asymmetry.

What are the symptoms of Snyder-Robinson syndrome?

Symptoms of Snyder-Robinson syndrome include the following:

• Delayed development evident in early childhood, affecting:
  • Speech
  • Mobility
  • Cognition
  • Intellectual ability in a person with SRS can range from mild to severe. Some individuals with SRS develop speech, often late, and speech difficulties are common.

• Low muscle mass and low muscle tone (hypotonia), resulting in:
  • Difficulty walking
  • Inability to walk
  • Unsteady gait

• Skeletal problems, particularly thinning of the bones (osteoporosis), that start in early childhood
• Abnormal side-to-side and back-to-front curvature of the spine
• Distinctive facial features, including:
  • Prominent lower lip
  • High, narrow roof of the mouth or an opening in the roof of the mouth (a cleft palate)
  • Differences in the size and shape of the right and left sides of the face (facial asymmetry)

Other signs and symptoms may include:

• Neurological problems
• Seizures
• Abnormalities of the genitalia and kidneys

What causes Snyder-Robinson syndrome?

Snyder-Robinson syndrome is caused by mutations in the SMS gene and is inherited in an X-linked recessive fashion. It results because of the mutated gene’s inability to convert spermidine to spermine.

How is Snyder-Robinson syndrome diagnosed?

A diagnosis of Snyder-Robinson syndrome can be made based on the clinical presentation and confirmed by sequencing of the spermine synthase (SMS) gene. Doctors also typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis.

What are the treatments for Snyder-Robinson syndrome?

Unfortunately, there is no cure for Snyder-Robinson syndrome. Treatment is directed toward the specific symptoms in each individual.

Where can I find out more Snyder-Robinson syndrome?

• National Organization for Rare Disorders (NORD)
• The Snyder-Robinson Foundation
• NIH