The loss of other genes in the deleted region may help explain why the features of Smith–Magenis syndrome vary among affected individuals. A small percentage of people with Smith–Magenis syndrome have a mutation in the RAI1 gene instead of a chromosomal deletion. These deletions and mutations lead to the production of an abnormal or nonfunctional version of the RAI1 protein. RAI1 is a transcription factor that regulates the expression of multiple genes, including several that are involved in controlling circadian rhythm, such as CLOCK. The groups led by James Lupski (Baylor College of Medicine) and Sarah Elsea (Virginia Commonwealth University) are in the process of studying the exact function of this gene in relation to Smith Magenis Syndrome.SMS is typically not inherited. This condition usually results from a genetic change that occurs during the formation of reproductive cells (eggs or sperm) or in early fetal development. People with Smith–Magenis syndrome most often have no history of the condition in their family. Diagnosis
SMS is usually confirmed by blood tests called chromosome (cytogenetic) analysis and utilize a technique called FISH (fluorescent in situ hybridization). The characteristic  micro-deletion was sometimes overlooked in a standard FISH test, leading to a number of people with the symptoms of SMS with negative results. The recent development of the FISH for 17p11.2 deletion test has allowed more accurate detection of this deletion. However, further testing is required for variations of Smith–Magenis syndrome that are caused by a mutation of the RAI1 gene as opposed to a deletion.
Children with SMS are often given psychiatric diagnoses such as autism, attention deficit/hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), attention deficit disorder (ADD) and/or mood disorders. Treatment
Treatment for Smith–Magenis syndrome relies on managing its symptoms. Children with SMS often require several forms of support, including physical therapy, behaviour therapy, occupational therapy and speech therapy. Support is often required throughout an affected persons lifetime. Medication is often used to address some symptoms. Melatonin supplements and trazodone are commonly used to regulate sleep disturbances. In combination with exogenous melatonin, blockade of endogenous melatonin production during the day by the adrenergic antagonist acebutolol can increase concentration, improve sleep and sleep timing and aid in improvement of behaviour. Other medications (such as risperidone) are sometimes used to regulate violent behavior. Eponym
The eponym Smith–Magenis refers to two scientists who described the condition in 1986, namely, Ann C. M. Smith, a genetic counselor at the National Institutes of Health, and R. Ellen Magenis, a pediatrician, medical geneticist and cytogeneticist at the Oregon Health Sciences University. See also
Serine hydroxymethyltransferase
Charcot-Marie-Tooth disease
Potocki-Lupski syndrome
Prader-Willi syndrome

References

This article incorporates public domain text from The U.S. National Library of Medicine


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