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Genetic and Rare Diseases Information Center (GARD)

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Ring chromosome 22


Other Names for this Disease

  • Chromosome 22 ring
  • R22
  • Ring 22
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Your Question

My 4-year-old son has been diagnosed with ring chromosome 22p12-q13. My son's doctors and I cannot find much information on it. I would appreciate if you could send me as much information as you might have. If there are support organizations, that would be helpful too.  

Our Answer

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

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: 6/5/2014

Are there any advocacy organizations for individuals and families with ring chromosome 22?

Yes. To view a list of these organizations, click on the Support Groups tab above.
Last updated: 7/11/2011

What are chromosomes?

Chromosomes are the structures that hold our DNA. Our DNA contains the instructions, called genes, which tell our bodies how to develop and function. Humans have 23 pairs of chromosomes, so 46 in total. One of each pair is inherited from our mother and the other from our father. Click here to view an illustration of a chromosome and DNA. Chromosomes vary in size. Each chromosome has a constriction point, called the centromere, which divides it into two sections. The shorter arm is called the p arm, and the longer arm is called the q arm.[1] To read more about chromosomes, click here.
Last updated: 7/11/2011

What is a ring chromosome?

A ring chromosome forms when the ends of both arms of the same chromosome are deleted and the remaining broken ends of the chromosome are 'sticky' and join together to make a ring shape. Usually it is the missing DNA that is significant. A person with a ring chromosome usually has a terminal deletion of both the short (p) and the long (q) arms of the chromosome, meaning that both ends of the chromosome are missing. However, if the ring chromosome is present as an extra chromosome, then it is the chromosomal material that has not been deleted that is significant. The material in the extra ring chromosome has effectively been duplicated. Some geneticists believe that poor growth and developmental delay are general features seen with ring chromosomes.[2]
Last updated: 7/11/2011

What is ring chromosome 22?

Ring chromosome 22 is a rare condition caused by having an abnormal chromosome 22 that forms a ring. In this chromosome abnormality, a segment on the short (p) arm and a segment on the long (q) arm of 22 are missing. The amount of material lost varies from person to person. The remaining ends of chromosome 22 have joined together to make a ring shape. Chromosome 22 is an acrocentric chromosome, meaning that the centromere is near one end, creating a very small short (p) arm that does not contain genes that are relevant to development. Thus, only the lost genes on the long (q) arm matter. Knowing the breakpoint in the long arm is likely more helpful. Most cases are sporadic (happen by chance) and occur in people with no history of the condition in their family.[3]
Last updated: 7/11/2011

What are the signs and symptoms of ring chromosome 22?

The associated signs and symptoms depend largely on where the breakpoint occurs on chromosome 22 and how much genetic material has been lost on the long (p) arm. Genetic material lost on the short (p) arm is usually irrelevant and does not cause physical or intellectual features. The breakpoints on the long (q) arm can be difficult to determine; but in ring chromosome 22, they are most likely to happen somewhere in the terminal segment of the distal band 22q13.[4]

In general, there is limited information on how chromosome abnormalities like ring chromosome 22 impact growth and development. Since each abnormality is usually so rare, there are few cases to learn from, let alone conduct research. It is generally difficult to say what the future will hold for affected individuals, because even when the chromosome abnormalities are similar, the health problems can vary widely. 

Over 100 cases have been reported on ring chromosome 22. While there is no consistent clinical picture, frequent findings of ring chromosome 22 include developmental delay, moderate to severe learning difficulties or intellectual disabilities, small head, absent or delayed speech, hypotonia, unsteady manner of walking, hyperactivity, autistic behaviors, seizures, and growth delay. Some affected individuals may also have relatively mild, non-specific physical features, whereas others may have more distinctive, potentially severe physical abnormalities.[3][4][5]

Unique is a source of information and support to families and individuals affected by rare chromosome disorders. On their Web site, they have a comprehensive information pamphlet on the signs and symptoms associated with ring chromosome 22. Click on the link below to view this information.
http://www.rarechromo.org/information/Chromosome%2022/Ring%2022%20FTNW.pdf
Last updated: 7/11/2011

What related research studies have there been for chromosome abnormalities that may be of interest?

The National Human Genome Research Institute (NHGRI) has completed an evaluation of patients with unresolved chromosome abnormalities. Through this study, the NHGRI may have discovered information pertinent to your son's chromosome finding. Further information about this study can be accessed at ClinicalTrials.gov, a database developed by the U.S. National Institutes of Health, through the National Library of Medicine to provide patients, family members, and members of the public with current information on clinical research studies. To read about this study, visit the hyperlink below. After you click on the study, review its information to determine if it provides you with useful information. Use the study’s contact information to learn more. Check this site often for regular updates or to search for specific chromosome abnormalities.
http://www.clinicaltrials.gov/ct/show/NCT00001639/

To locate information resulting from this completed study, you can either e-mail or call the National Library of Medicine (NLM) Customer Service. Include the title of the study, the study ID number, and the NLM Identifier, and a librarian at NLM can assist you in searching the medical literature for published results on the completed clinical trial.

National Library of Medicine Customer Service
Toll-free: 1-888-346-3656
E-mail: custserv@nlm.nih.gov/

The Chromosome Deletion Outreach lists a number of ongoing chromosome research studies. You can read more about these studies at the following link to the CDO Web page.
http://www.chromodisorder.org/CDO/Resources/LatestResearch.aspx  
Last updated: 7/11/2011

References
Other Names for this Disease
  • Chromosome 22 ring
  • R22
  • Ring 22
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.