What is Smith-Magenis Syndrome?
How is Smith-Magenis Syndrome diagnosed?
What is the treatment for Smith-Magenis Syndrome?
How rare is Smith-Magenis Syndrome?
What is the current status of research on Smith-Magenis syndrome?
Is Smith-Magenis syndrome recessive or dominant?
In the context of medical genetics, an autosomal dominant disorder is caused when a single copy of the mutant allele is present. Males and females are affected equally, and can both transmit the disorder with a risk of 50% for each child of inheriting the mutant allele.
What is the life expectancy of a person with Smith-Magenis syndrome?
Could Smith-Magenis syndrome have been prevented?
Are there prenatal tests for Smith-Magenis syndrome?
What does SMS mean in medical terms?
What is SMS autism?
What are symptoms of SMS?
What is the ICD10 code for Smith Magenis Syndrome? And the ICD9 code for Smith Magenis Syndrome?
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What is the history of Smith Magenis Syndrome?
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Epidemiology
Smith-Magenis syndrome (SMS) has an estimated prevalence of 1/15,000-25,000 and has been identified worldwide in all ethnic groups, but is probably underdiagnosed. Males and females are affected equally.
Clinical description
Patients have a recognizable clinical picture. Craniofacial features include brachycephaly, a broad square-shaped face, synophrys, mildy upslanted palpebral fissures, midface retrusion with relative prognathism with age, and an everted upper lip with a ”tented” appearance.
Etiology
SMS is typically a sporadic disorder caused either by a 17p11.2 deletion encompassing the retinoic acid-induced 1 (RAI1) gene (90%) or a mutation of the gene (10%). Patients with a mutation can have a less severe phenotype, and manifestations may have a later onset in the least severe cases.
Diagnostic methods
Diagnosis is based on initial clinical suspicion followed by molecular confirmation of the genetic defect. Careful history-taking for birth defects, sleep disturbance, delayed milestones, chronic ear infections, self-injurious behaviors, and family history are important to recognize the characteristic features.
Differential diagnosis
Differential diagnoses include Down syndrome, Williams syndrome, brachydactyly-intellectual deficit syndrome (del 2q37), and Kleefstra syndrome.
Antenatal diagnosis
Almost all cases correspond to a single occurrence in a family, but prenatal testing can be offered for at-risk pregnancies where the genetic alteration has been previously identified in an affected family member.
How to make a diagnosis for a genetic disorder?
Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.
Is Smith-Magenis syndrome inherited?
Most cases of Smith-Magenis syndrome (SMS) are not inherited. SMS usually occurs due to a random genetic change in a parent’s sperm or egg cell, or very early in embryonic development. Most people with SMS have no family history of the condition. [1] [3]
Can a parent cause a child to have SMS?
In a very small number of cases, SMS in a child can result from a parent having a balanced translocation (resulting in a deletion in the child), or from a mutation in the RAI1 gene that was inherited from a parent. [2] . Very rarely, parental germline mosaicism has been reported to cause SMS in a child.