22q11.2 deletion syndrome

What causes 22q11.2 deletion syndrome?

22q11.2 deletion syndrome is caused by a missing piece (deletion) of part of chromosome 22 in each cell. The deletion occurs near the middle of the chromosome on the q arm at a location known as q11.2.

Most people with 22q11.2 deletion syndrome are missing a piece of chromosome 22 that contains about 30 to 40 genes, many of which have not been well characterized; however, some people have smaller deletions. Researchers are working to learn more about all of the genes that contribute to the features of 22q11.2 deletion syndrome. The deletion of a particular gene, TBX1, is thought to be responsible for many of the syndrome's characteristic signs and symptoms. Loss of this gene may also contribute to behavioral problems. The loss of another gene, COMT , may also cause increased risk of behavioral problems and mental illness. The other genes that are deleted likely contribute to the various features of 22q11.2 deletion syndrome.

Last updated on 05-01-20

How is 22q11.2 deletion syndrome inherited?

Most cases of 22q11.2 deletion syndrome are not inherited from a parent and are caused by a random error during the formation of egg or sperm cells, or during early fetal development. In about 10% of cases, the deletion is inherited from a parent with the deletion.

When the deletion is inherited, it is inherited in an autosomal dominant pattern. This means that having the deletion in only one copy of chromosome 22 in each cell is enough to cause features of the condition. There is nothing that either parent can do, before or during a pregnancy, to cause a child to have this condition.

When a person with a deletion that causes an autosomal dominant condition has children, each child has a 50% (1 in 2) chance to inherit that deletion.

Last updated on 05-01-20

Is there any difference between having the 22q11.2 deletion on one (heterozygous) versus both (homozygous) copies of chromosome 22?

Most people with 22q11.2 deletion syndrome are missing a sequence of about 3 million DNA building blocks (base pairs) on one copy of chromosome 22 in each cell. This region contains 30 to 40 genes, many of which have not been well characterized. A small percentage of affected individuals have shorter deletions in the same region. We are unaware of any cases of homozygous 22q11.2 deletions. However, in addition to the loss of genes in the 22q11.2 region (e.g., TBX1 and COMT), the highly variable signs and symptoms of 22q11.2 deletion syndrome are in part due to changes outside the deleted region or on the remaining (non-deleted) copy of chromosome 22 (e.g., SNAP29).

Last updated on 05-01-20

Is feeling faint, or fainting, a symptom of 22q11.2 deletion syndrome?

We are not aware of published reports suggesting that feeling faint, or fainting (called syncope ) is a symptom directly associated with 22q11.2 deletion syndrome; however, syncope may occur as a result of features associated with 22q11.2 deletion syndrome. For example, syncope has been reported in people with hypoparathyroidism and people with low levels of calcium in the blood (hypocalcemia).

People who feel faint should speak with a health care provider to determine the underlying cause and discuss treatment options.

Last updated on 05-01-20

What is 'complete' versus 'partial' DiGeorge syndrome?

DiGeorge syndrome was once thought to be a distinct syndrome, but is now recognized to fall within the disorder spectrum known as 22q11.2 deletion syndrome. Symptoms of what was formerly known as DiGeorge syndrome were variable and the underlying cause (deletions of 22q11.2) is also responsible for related/overlapping syndromes. Terms such as 'complete' and 'partial' DiGeorge syndrome have been used in reference to individual cases which had all the characteristic signs and symptoms (e.g., hypoparathyroidism, absent thymus, and congenital heart disease) verses those with only some of them.

Last updated on 05-01-20

Are thyroid problems associated with 22q11.2 deletion syndrome?

Yes. Some people with 22q11.2 deletion syndrome develop autoimmune diseases that can affect the thyroid. This includes Grave's disease, a disease that causes the thyroid gland to produce too much hormone (hyperthyroidism) and hypothyroidism, a condition in which the thyroid gland does not produce enough hormone.

Last updated on 05-01-20

Why might calcium be given to a child with 22q11.2 deletion syndrome?

Many people with 22q11.2 deletion syndrome develop hypoparathyroidism. Hypoparathyroidism is a condition in which too little parathyroid hormone (PTH) is produced. This condition causes low levels of calcium and high levels of phosphorus in the blood. Common symptoms may include tingling, muscle cramps, pain, dry hair, brittle nails, dry, scaly skin, cataracts, weakened tooth enamel in children, muscle spasms called tetany (can lead to spasms of the larynx, causing breathing difficulties), and seizures. The goal of treatment is to restore the calcium and mineral balance in the body.

We recommend you discuss concerns regarding your child's treatment with his physician.

Last updated on 05-01-20

Can 22q11.2 deletion syndrome affect the central nervous system?

Yes. 22q11.2 deletion syndrome can affect the central nervous system. Examples of central nervous system abnormalities, including brain abnormalities (e.g., cerebellar atrophy, polymicrogyria, enlarged sylvian fissures), neural tube defects, tethered cord, and seizures.

Last updated on 05-01-20

How might seizures be treated?

There are many treatment options available for children and adults with seizures. It can be challenging for a family to find the medication or procedure that works best for their child. We suggest that you speak with your child's health care provider about working with a physician who specializes in treating epilepsy. The Epilepsy Foundation provides information that can assist you in finding an epilepsy specialist in your area. To access this information, click here.

You can find more information on seizures and seizure disorders including information on treatment at the following links from MedlinePlus, the National Library of Medicine Web site designed to help you research your health questions.

Additional information on seizures can also be found by visiting the following Web page developed by the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health (NIH).

Last updated on 05-01-20

Since my son is having seizures now, could it mean that he has a different syndrome?

Some individuals with 22q11.2 deletion syndrome do develop seizures. However, if you have questions regarding your son's diagnosis, we encourage you to speak with his healthcare provider. You may find it helpful to meet with a genetics professional, if you have not already done so.

Last updated on 05-01-20

Are seizures associated with 22q11.2 deletion syndrome?

Yes. Some people with 22q11.2 deletion syndrome have seizures. The seizures may be evidence of an underlying central nervous system abnormality or can result due to low levels of the parathyroid hormone.

Last updated on 05-01-20

Is being overweight, or having difficulty losing weight, a symptom of 22q11.2 deletion syndrome?

Being overweight, or having difficulty losing weight, does not appear to be a symptom of 22q11.2 deletion syndrome specifically. However, an affected individual may have another condition causing this symptom that is associated with 22q11.2 deletion syndrome. For example, some autoimmune disorders such as hypothyroidism are associated with 22q11.2 deletion syndrome; hypothyroidism can cause weight gain or difficulty losing weight.

Last updated on 05-01-20

What is the long-term outlook for 22q11.2 deletion syndrome?

There is a wide range of symptoms and severity among people with 22q11.2 deletion syndrome. The long-term outlook for each person depends on the specific signs and symptoms each individual has.

Factors that may impact the severity of the disease and the likelihood for a shortened lifespan include whether or not a congenital heart defect is present and how severe the defect is, as well as the severity of immune system problems. For instance, individuals with complete absence of the thymus gland and absent T cells may pass away prematurely.

Last updated on 05-01-20

How common is 22q11.2 deletion syndrome?

It is estimated that between 1 in 4,000 and 1 in 6,395 individuals have 22q11.2 deletion syndrome. It is suspected that 22q11.2 deletion is more common than previously reported given how much symptoms can vary and the likelihood that some individuals remain undiagnosed.

Last updated on 05-01-20

Selected Full-Text Journal Articles

Free full text-22q11.2 deletion syndrome

Fung WLA, Butcher NJ, Costain G, et al. Practical guidelines for managing adults with 22q11.2 deletion syndrome. 2015;17(8):599-609. doi:10.1038/gim.2014.175.

Last updated on 04-27-20

Where To Start

The International 22q11.2 Foundation Inc.

The International 22q11.2 Deletion Syndrome Foundation, Inc. provides support, resources, and information for 22q11.2 deletion syndrome

Last updated on 04-27-20

Name: Chromosome Disorder Outreach CDO PO Box 724
Boca Raton, FL, 33429 , United States
Phone: +1-561-395-4252 Email: https://chromodisorder.org/contact/ Url: https://chromodisorder.org/
Name: Chromosome 22 Central - US Office 7108 Partinwood Drive
Fuquay-Varina, NC, 27526 , United States
Phone: 919-567-8167 Email: usinfo@c22c.org Url: http://www.c22c.org
Name: Unique – Rare Chromosome Disorder Support Group G1, The Stables Station Road West
Surrey RH8 9EE
United Kingdom
Phone: +44 (0)1883 723356 Email: info@rarechromo.org Url: https://www.rarechromo.org/
Name: The 22q11 Group PO Box 1302 Milton Keynes MK13 0LZ
United Kingdom
Phone: +44 1908 320 852 Email: 22q11@melcom.cix.co.uk
Name: The International 22q11.2 Foundation Inc. PO Box 532
Matawan, NJ, 07747, United States
Phone: 877-739-1849 Email: info@22q.org Url: http://www.22q.org
Name: International DiGeorge / VCF Support Network c/o Family Voices of New York 46 1/2 Clinton Avenue
Cortland, NY, 13045, United States
Phone: 607-753-1621 (day); 607-753-1250 (evening) Fax : 607-758-7420
Name: 22q Foundation Australia & New Zealand Email: https://www.22q.org.au/contact-us Url: https://www.22q.org.au/

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