Chromosome 22q11.2 duplication syndrome

Diagnosis and Testing

How do I get tested for 22q11.2 duplication syndrome?

Genetic testing for 22q11.2 duplication syndrome can be ordered by your primary care physician, medical geneticist, or other specialist physician. There are many commercial laboratories that offer genetic testing for 22q11.2 duplication syndrome. Chromosome 22q11.2 duplication syndrome is most commonly diagnosed by technology known as array comparative genomic hybridization (aCGH), or chromosome microarray analysis, though there are other types of genetic testing technology that could detect 22q11.2 duplication syndrome. This testing is most commonly performed on blood, though, depending on the laboratory used, 22q11.2 duplication syndrome could also be diagnosed by specialized testing of saliva, skin or other tissue samples. Depending upon the specific testing done and the laboratory used, a typical turn around time for results is approximately 4-6 weeks.

If you or a family member have been diagnosed with 22q11.2 duplication syndrome, a medical geneticist or genetic counselor can help interpret your results, including explaining the specific size and exact location ("address") on chromosome 22 of the duplication. This information should be available on the laboratory report and is important information if you are going to read medical articles describing patients with a 22q11.2 duplication, because individuals with 22q11.2 duplication do not all have the exact same size and chromosome location of their duplication, which affects which genes are involved in their specific duplication. This variation in the specifics of the duplication from individual to individual may explain some, but not all, of the variability in symptoms from one individual with 22q11.2 duplication syndrome to another.

References
  • Unique. (2012). 22q11.2 duplications. Retrieved February 20, 2016, from http://www.rarechromo.org/information/Chromosome%2022/22q11.2%20duplications%20FTNW.pdf
  • Firth HV. 22q11.2 Duplication. 2009 Feb 17 [Updated 2013 Nov 21]. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2016. Available from: http://www.ncbi.nlm.nih.gov/books/NBK3823/
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More Diagnosis and Testing Content

Who in my family should be tested for 22q11.2 duplication syndrome?

Is it recommended to test children for 22q11.2 duplication syndrome?

Is Prenatal testing/PGD available for 22q11.2 duplication syndrome?

Is there routine newborn testing for 22q11.2 duplication syndrome?

Should you do a biopsy for 22q11.2 duplication syndrome?

Who in my family should be tested for 22q11.2 duplication syndrome?

When an individual is diagnosed as having 22q11.2 duplication syndrome, genetic testing should be considered for that individual's parents (to determine if the 22q11.2 duplication was inherited from a parent who also has 22q11.2 duplication, or appears to have occurred de novo (new in the affected individual)). The parents of an individual with 22q11.2 duplication syndrome do not have to have known symptoms of 22q11.2 duplication syndrome in order to have 22q11.2 duplication.

If the person with 22q11.2 duplication has children, each child has a 1 in 2 (50%) chance of either inheriting or not inheriting the 22q11.2 duplication from their affected parent, and so genetic testing in the children of an individual with 22q11.2 duplication syndrome should be considered.

During a consultation with a medical geneticist or genetic counselor, it is typical for a family's genetic family history (pedigree) to be reviewed, and as part of that process the geneticist or genetic counselor will review which of an individual's relatives should be offered testing for 22q11.2 duplication syndrome. If you are interested in locating a genetic counselor in the United States or Canada, there is a searchable directory on the National Society of Genetic Counselors website called "Find a Genetic Counselor".

References
  • Genetics Home Reference. (2011). 22q11.2 duplication. Retrieved February 20, 2016, from http://ghr.nlm.nih.gov/condition/22q112-duplication
  • Firth HV. 22q11.2 Duplication. 2009 Feb 17 [Updated 2013 Nov 21]. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2016. Available from: http://www.ncbi.nlm.nih.gov/books/NBK3823/
Is it recommended to test children for 22q11.2 duplication syndrome?

The common symptoms reported in 22q11.2 duplication syndrome (developmental delay, intellectual disability, slow growth leading to short stature and weak muscle tone (hypotonia)) are not sufficiently distinct enough to 22q11.2 duplication syndrome for this syndrome to be specifically suspected on these symptoms alone. However, it is reasonable to consider evaluation by a medical geneticist when an individual has these symptoms, and the testing needing to diagnose 22q11.2 duplication syndrome is routinely ordered by a medical geneticist when the possibility of a chromosome change like 22q11.2 duplication is suspected.

There is a growing appreciation that some individuals have more than one genetic diagnosis as the cause of their developmental problems. If an individual with severe developmental problems and/or multiple congenital anomalies is diagnosed with a 22q11 duplication, it may be appropriate to consider further testing to determine whether additional genetic diagnoses are contributing to these physical symptoms.

References
  • Firth HV. 22q11.2 Duplication. 2009 Feb 17 [Updated 2013 Nov 21]. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2016. Available from: http://www.ncbi.nlm.nih.gov/books/NBK3823/
Is Prenatal testing/PGD available for 22q11.2 duplication syndrome?

Prenatal diagnosis during pregnancy and preimplantation genetic diagnosis (PGD) as a step in assisted reproductive technology for 22q11.2 duplication syndrome is technically possible. Targeted testing specifically for 22q11.2 duplication syndrome could be performed for parents who have a known risk for 22q11.2 duplication syndrome in their children. Additionally, the genetic technology which can diagnose 22q11.2 duplication syndrome along with many other chromosome changes is becoming more commonly used for genetic screening in prenatal and preimplantation genetic diagnosis situations.

Genetic counselors are available to discuss reproductive related issues including the risk of chromosome changes such as 22q11.2 duplication syndrome in a pregnancy as well as review an individual's pregnancy screening and testing options. For more information, you can locate a genetic counselor in your area on the National Society of Genetic Counselors "Find a Genetic Counselor" searchable directory.

References
  • Firth HV. 22q11.2 Duplication. 2009 Feb 17 [Updated 2013 Nov 21]. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2016. Available from: http://www.ncbi.nlm.nih.gov/books/NBK3823/
  • Unique. (2012). 22q11.2 duplications. Retrieved February 20, 2016, from http://www.rarechromo.org/information/Chromosome%2022/22q11.2%20duplications%20FTNW.pdf
Is there routine newborn testing for 22q11.2 duplication syndrome?

No, 22q11.2 duplication syndrome is not a condition that is tested for in routine newborn screening. The genetic testing which would detect 22q11.2 duplication syndrome is a test that is only routinely done in individuals when there is reason to suspect the possibility of a chromosome change, either because of the individual's health or development or family history.

If there is reason to suspect that a baby has 22q11.2 duplication syndrome or another chromosome change, genetic testing would be an option at any age.

The specific conditions included in the general population newborn screening are determined by individual states. More information about newborn screening, including which disorders are included in the newborn screening panel in a particular state, is available at http://www.babysfirsttest.org.

Should you do a biopsy for 22q11.2 duplication syndrome?

While it would be technically possible to diagnose 22q11.2 duplication syndrome on tissue obtained from a biopsy, it is not necessary. Biopsies are more invasive than obtaining a saliva or blood sample, and so it is not recommended for testing. Many commercial laboratories offer the genetic testing that would detect 22q11.2 duplication syndrome on both blood and saliva samples, making biopsy unnecessary and unjustified.

References
  • Firth HV. 22q11.2 Duplication. 2009 Feb 17 [Updated 2013 Nov 21]. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2016. Available from: http://www.ncbi.nlm.nih.gov/books/NBK3823/

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