22q11.2 duplication syndrome

Overview

What is 22q11.2 duplication?

22q11.2 duplication means that there is a very small extra piece of genetic material on the long arm of the 22nd chromosome. Most often this extra piece is a copy (or duplicate) of the piece next to it.

Chromosomes are found in most cells of our bodies and contain the genetic information or blueprints for our body to grow and function. These chromosomes come in 23 pairs. The first 22 pairs are numbered 1 through 22 and the 23rd "pair" are the sex chromosomes (X and Y). Based on their shape, chromosomes are said to have two "arms", a short arm called "p" and a long arm called "q".

Having 22q11.2 duplication does not mean you have a medical condition. In fact, some people with the duplication do not have any symptoms. However, people who have been identified as having this duplication by genetic testing often have other health or developmental problems which led to the testing (but are not necessarily caused by the duplication). Because this is a relatively rare chromosome difference, most doctors are not familiar with it.

Prior to 2006, a 22q11.2 duplication was only reported after very specialized genetic tests called Fluorescence in situ hybridization (FISH) or Multiplex ligation-dependent probe amplification (MLPA) for that area on chromosome 22 were done. After 2006, doctors started using a new test called "array comparative genomic hybridization" or chromosomal microarray that was able to the find very small changes in chromosomes like the 22q11.2 duplication more routinely. Although many things have been learned about 22q11.2 duplications, it is still unclear in 2016 why having an extra piece of material in 22q11.2 affects some people's health and development but not others, or if it causes any problems at all. Complicating the question is the knowledge that most information we have on the 22q11.2 duplication was learned from people searching for a cause for health problems and developmental delays. This makes it unclear if a 22q11.2 duplication is a main cause of birth defects and developmental delays, a common change that doesn't cause problems, or a partial cause of health problems that needs to be present with other genetic changes before problems happen. Given the range of health problems, treatment for people with 22q11.2 duplication should be very specific to the person's needs.

Working with a doctor or genetic counselor familiar with 22q11.2 duplication can very helpful in understanding the implications (if any) of 22q11.2 duplication for a specific person and develop a good monitoring and treatment plan. Several resources for locating a genetics professional in your community are available online such as the National Society of Genetic Counselors. Genetic counselors can be found on the National Society of Genetic Counselors website.You can search by location, name, area of practice/specialization, and/or ZIP Code. The Genetic and Rare Diseases Information Center (GARD) , a service of the National Institutes of Health, provides a guide to finding specialists in particular genetic and rare conditions. (https://rarediseases.info.nih.gov/resources/pages/25/how-to-find-a-disease-specialist).

There are several support groups that were created to connect, help, and provide information for people living with 22q11.2 duplication and their families. One such group is the support group Chromosome 22 Central (also called C22C) that can be found at the website http://www.c22c.org/. This group supports patients with all different types of chromosome 22 changes from 22q11.2 duplication syndrome to unique changes in chromosome 22 only seen a very small amount of people. They provide basic information on their website, but their primary mission is connecting patients and families with each other to learn from one another. The International 22q11.2 Foundation, Inc. focuses on support and advocacy for individuals and families affected by a duplication OR deletion in the 22q11.2 region (http://www.22q.org/about-22q/).

Firth HV, 22q11.2 Duplication. GeneReviewshttp://www.ncbi.nlm.nih.gov/books/NBK3823/

22q11 MicroduplicationChromosome 22 Central (C22C) Support for Disorders of Chromosome 22. http://www.c22c.org/22q11dup.htm

The International 22q11.2 Foundation, Inc.http://www.22q.org/about-22q/

UNIQUE 22q11.2 duplicationshttp://www.rarechromo.org/information/Chromosome%2022/22q11.2%20duplications%20FTNW.pdf

Chromosome Disorder Outreachhttp://chromodisorder.org/Display.aspx?ID=35

GARD, https://rarediseases.info.nih.gov/resources/pages/25/how-to-find-a-disease-specialist

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