Snyder–Robinson syndrome

Snyder–Robinson Syndrome

Snyder–Robinson syndrome (SRS) is a rare genetic disorder characterized by intellectual disability, muscle and bone abnormalities, and other systemic manifestations. It is an X-linked recessive condition, meaning it primarily affects males, while females are typically carriers.

Genetics

Snyder–Robinson syndrome is caused by mutations in the SMS gene, which encodes the enzyme spermine synthase. This enzyme is crucial in the polyamine biosynthesis pathway, responsible for converting spermidine into spermine. Polyamines like spermine are essential for cellular growth, differentiation, and stability.

The SMS gene is located on the X chromosome at Xp22.11. Mutations in this gene lead to a deficiency of spermine synthase, resulting in an imbalance of polyamines, which is thought to underlie the clinical features of the syndrome.

Clinical Features

Individuals with Snyder–Robinson syndrome typically present with:

• Intellectual Disability: Ranging from mild to severe, often accompanied by speech delays.
• Hypotonia: Reduced muscle tone, which can affect motor skills.
• Osteoporosis: Increased bone fragility, leading to frequent fractures.
• Facial Dysmorphism: Distinctive facial features may include a prominent forehead, deep-set eyes, and a prominent jaw.
• Seizures: Some individuals may experience epileptic seizures.
• Other Features: These can include kyphoscoliosis, a high-arched palate, and growth retardation.

Diagnosis

Diagnosis of Snyder–Robinson syndrome is based on clinical evaluation, family history, and genetic testing. Molecular genetic testing can confirm the diagnosis by identifying mutations in the SMS gene.

Management

There is currently no cure for Snyder–Robinson syndrome. Management is symptomatic and supportive, focusing on:

• Educational Support: Special education programs tailored to the individual's needs.
• Physical Therapy: To improve muscle tone and motor skills.
• Orthopedic Interventions: For managing bone abnormalities and fractures.
• Seizure Management: Antiepileptic drugs may be prescribed for seizure control.

Prognosis

The prognosis for individuals with Snyder–Robinson syndrome varies depending on the severity of symptoms. With appropriate management, individuals can lead fulfilling lives, although they may require lifelong support.

Research

Ongoing research aims to better understand the pathophysiology of Snyder–Robinson syndrome and explore potential therapeutic interventions. Studies are focusing on the role of polyamines in cellular processes and how their imbalance affects individuals with the syndrome.

Also see

• X-linked recessive inheritance
• Intellectual disability
• Osteoporosis
• Genetic testing

NIH genetic and rare disease info

• NIH info on Snyder–Robinson syndrome

Snyder–Robinson syndrome is a rare disease.