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Genetic and Rare Diseases Information Center (GARD)

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Smith-Magenis syndrome

Other Names for this Disease
  • Chromosome 17p11.2 deletion syndrome
  • SMS
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Your Question

Is it true that Smith-Magenis syndrome become more difficult to diagnose through genetic testing if the child is older than 24 months?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

Does Smith-Magenis syndrome become more difficult to diagnose through genetic testing if the child is older than 24 months?

No. Genetic testing can be performed at any age. Each person's genetic make-up is set during conception and remains the same throughout their lifetime. Most individuals with Smith-Magenis are missing a piece of genetic material from a specific region of chromosome 17. This missing region of genetic material is absent from conception or early fetal life, and would be expected to remain missing throughout their lifespan.  A clinical diagnosis, which is less definitive than genetic testing, can be a little bit more difficult to arrive at. For example, some physical features of Smith-Magenis syndrome can be subtle in infancy and become more distinct later in childhood or adulthood.[1]
Last updated: 5/11/2012

Where can I find information on laboratories that are offering genetic testing for Smith-Magenis syndrome?

GeneTests lists the names of laboratories that are performing genetic testing for Smith-Magenis syndrome. To view the contact information for the clinical laboratories, conducting testing click here.  To access the contact information for the research laboratories performing genetic testing, click here

Please note:  Most of the laboratories listed through GeneTests do not accept direct contact from patients and their families; therefore, if you are interested in learning more, you will need to work with a health care provider or a genetics professional.  In the Genetic Services section of this letter we provide a list of online resources that can assist you in locating a genetics professional near you.


Last updated: 5/11/2012

How can I find a genetics professional in my area?

Genetics clinics are a source of information for individuals and families regarding genetic conditions, treatment, inheritance, and genetic risks to other family members. More information about genetic consultations is available from Genetics Home Reference. To find a genetics clinic, we recommend that you contact your primary healthcare provider for a referral.

The following online resources can help you find a genetics professional in your community:
Last updated: 10/18/2013