Smith–Magenis syndrome

A genetic disorder characterized by developmental delay and behavioral problems

Smith–Magenis syndrome
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Synonyms	N/A
Pronounce	N/A
Specialty	N/A
Symptoms	Developmental delay, sleep disturbances, behavioral problems
Complications	N/A
Onset	Congenital
Duration	Lifelong
Types	N/A
Causes	Deletion or mutation of the RAI1 gene
Risks	N/A
Diagnosis	Genetic testing
Differential diagnosis	N/A
Prevention	N/A
Treatment	Symptomatic management
Medication	N/A
Prognosis	N/A
Frequency	1 in 15,000 to 25,000 births
Deaths	N/A

Smith–Magenis syndrome (SMS) is a complex developmental disorder that affects multiple organ systems. It is primarily characterized by distinctive facial features, developmental delay, sleep disturbances, and behavioral problems. SMS is caused by a deletion or mutation of the RAI1 gene on chromosome 17.

Presentation

Individuals with Smith–Magenis syndrome often present with a variety of symptoms that can vary in severity. Common features include:

• Developmental delay: Most children with SMS experience delays in reaching developmental milestones such as sitting, walking, and talking.
• Behavioral problems: These can include self-injurious behaviors, aggression, and temper tantrums. A characteristic feature is the "self-hugging" behavior.
• Sleep disturbances: Individuals with SMS often have an inverted circadian rhythm, leading to sleep problems such as difficulty falling asleep and frequent nighttime awakenings.
• Distinctive facial features: These may include a broad, square-shaped face, deep-set eyes, and a prominent jaw.
• Other features: Short stature, scoliosis, and hearing loss are also common.

Genetics

Smith–Magenis syndrome is typically caused by a deletion of a small piece of chromosome 17, specifically 17p11.2, which includes the RAI1 gene. In some cases, a mutation in the RAI1 gene itself can cause the syndrome. The RAI1 gene is believed to play a crucial role in the development of the nervous system and the regulation of circadian rhythms.

Diagnosis

Diagnosis of Smith–Magenis syndrome is confirmed through genetic testing, which can identify the deletion or mutation of the RAI1 gene. Clinical features and family history are also considered in the diagnostic process.

Management

There is no cure for Smith–Magenis syndrome, and treatment is focused on managing symptoms and improving quality of life. This may include:

• Behavioral therapy: To address behavioral issues and improve social skills.
• Educational support: Special education services tailored to the individual's needs.
• Sleep management: Strategies to improve sleep patterns, which may include melatonin supplements or other medications.
• Medical interventions: For associated conditions such as scoliosis or hearing loss.

Prognosis

The prognosis for individuals with Smith–Magenis syndrome varies. With appropriate support and interventions, many individuals can lead fulfilling lives, although they may require lifelong assistance.

Epidemiology

Smith–Magenis syndrome is estimated to occur in 1 in 15,000 to 25,000 births. It affects both males and females equally and has been reported in various ethnic groups.

History

Smith–Magenis syndrome was first described in 1986 by Ann C. M. Smith and Ellen Magenis, who identified the chromosomal deletion associated with the disorder.

Also see

• Chromosome 17
• Genetic disorders
• Developmental delay
• Behavioral therapy