Smith-Magenis Syndrome (SMS)
What is Smith-Magenis syndrome (SMS)?
Smith-Magenis syndrome (SMS) is a developmental disorder that affects multiple organ systems of the body. It is characterized by a pattern of abnormalities that are present at birth (congenital), as well as behavioral and cognitive problems.
What are the symptoms of Smith-Magenis syndrome (SMS)?
- Mild to moderate intellectual disability
- Delayed speech and language skills
- Broad, square-shaped face with deep-set eyes and prominent jaw
- Sleep disturbances
- Behavioral issues
Other, less frequent symptoms include:
- Short stature
- Reduced sensitivity to pain and temperature
- Hoarse voice
- Ear abnormities leading to hearing loss
- Vision problems
What causes Smith-Magenis syndrome (SMS)?
Most people with Smith-Magenis syndrome have a deletion of genetic material from a specific region of chromosome 17. The loss of one specific gene – the retinoic acid induced 1 or RAI1 – is responsible for most of the characteristic features of SMS.
A small percentage of people with SMS have just a mutation in the RAI1 gene (not a deletion of the larger part of the chromosome).
How is Smith-Magenis syndrome (SMS) diagnosed?
The diagnosis of SMS is confirmed when deletion 17p11.2 or RAI1 gene mutation is identified. This diagnosis is reached after identification of characteristic symptoms, a detailed patient and family history, a thorough clinical evaluation, and a variety of genetic tests.
Specialized exams include:
- Fluorescent in situ hybridization (FISH)
- Chromosomal microarray analysis
- Chromosomal study known as G-band analysis
- Molecular genetic testing
What treatments are available for Smith-Magenis syndrome (SMS)?
There is currently no cure or direct treatment for SMS, only symptom management.
Services that may be beneficial include special remedial education, speech/language therapy, occupational therapy, and sensory integration therapy.