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Disease at a Glance

Summary
Monosomy 22q13.3, also known as Phelan-McDermid syndrome, is a chromosome disorder caused by the loss (deletion) of a small piece of chromosome 22. The deletion occurs near the end of the long arm (or q arm) of the chromosome at a location designated as q13.3. Not everyone with monosomy 22q13.3 will have the same medical, developmental, or behavioral problems (features). Common problems include low muscle tone (hypotonia), intellectual disability, developmental delays especially delayed or absent speech, and tendency to overheat. Children may be tall and thin. Differences in other physical features are usually mild and may include long eyelashes, down slanting eyes, large ears, ears without normal folding, bulb-like tip of nose, pointed chin, large hands, and toenails that flake off as infants and then become hard and brittle as age. Unusual behaviors may include mouthing or chewing on non-food items, decreased perception of pain, and autistic-like behaviors such as flapping of hands and repetitive motions. Most reported cases of monosomy 22q13.3 are caused by 22q13.3 deletions, which usually includes many genes. The loss or the variation of a particular gene on chromosome 22, called the SHANK3 gene, is likely responsible for many of the common features associated with monosomy 22q13.3, especially intellectual disability, speech problems, low muscle tone, and developmental delay. Additional genes within the deleted area probably contribute to other features of the syndrome. In most cases, a larger deletion increases the number and severity of associated features, especially the severity of low muscle tone, developmental delay, differences in physical features, speech, and autism-like behavior. Smaller deletions located closer to the tip of the 22q seem to be associated with fewer medical, developmental, and behavioral problems.
Summary
Monosomy 22q13.3, also known as Phelan-McDermid syndrome, is a chromosome disorder caused by the loss (deletion) of a small piece of chromosome 22. The deletion occurs near the end of the long arm (or q arm) of the chromosome at a location designated as q13.3. Not everyone with monosomy 22q13.3 will have the same medical, developmental, or behavioral problems (features). Common problems include low muscle tone (hypotonia), intellectual disability, developmental delays especially delayed or absent speech, and tendency to overheat. Children may be tall and thin. Differences in other physical features are usually mild and may include long eyelashes, down slanting eyes, large ears, ears without normal folding, bulb-like tip of nose, pointed chin, large hands, and toenails that flake off as infants and then become hard and brittle as age. Unusual behaviors may include mouthing or chewing on non-food items, decreased perception of pain, and autistic-like behaviors such as flapping of hands and repetitive motions. Most reported cases of monosomy 22q13.3 are caused by 22q13.3 deletions, which usually includes many genes. The loss or the variation of a particular gene on chromosome 22, called the SHANK3 gene, is likely responsible for many of the common features associated with monosomy 22q13.3, especially intellectual disability, speech problems, low muscle tone, and developmental delay. Additional genes within the deleted area probably contribute to other features of the syndrome. In most cases, a larger deletion increases the number and severity of associated features, especially the severity of low muscle tone, developmental delay, differences in physical features, speech, and autism-like behavior. Smaller deletions located closer to the tip of the 22q seem to be associated with fewer medical, developmental, and behavioral problems.
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Resource(s) for Medical Professionals and Scientists on This Disease:

About Monosomy 22q13.3

Many rare diseases have limited information. Currently GARD aims to provide the following information for this disease:

  • Population Estimate:This section is currently indevelopment.
  • Symptoms:May start to appear as a Newborn and as an Infant.
  • Cause:This disease is caused by changes in the way information is arranged into chromosomes.
  • Organizations:Patient organizations are available to help find a specialist, or advocacy and support for this specific disease.
  • Categories:Birth DefectsGenetic DiseasesNeurological DiseasesSkin Diseases
When Do Symptoms of Monosomy 22q13.3 Begin?
Symptoms of this disease may start to appear as a Newborn and as an Infant.

The age symptoms may begin to appear differs between diseases. Symptoms may begin in a single age range, or during several age ranges. The symptoms from some diseases may begin at any age. Knowing when symptoms began to appear can help medical providers find the correct diagnosis.
Prenatal
Before Birth
Newborn Selected
Birth-4 weeks
Infant Selected
1-23 months
Child
2-11 years
Adolescent
12-18 years
Adult
19-65 years
Older Adult
65+ years
Symptoms may start to appear as a Newborn and as an Infant.

Symptoms

The types of symptoms experienced, and their intensity, may vary among people with this disease. Your experience may be different from others, and you should consult your primary care provider (PCP) for more information.

This list does not include all possible symptoms related to this disease, but they may include:
Musculoskeletal System Musculoskeletal System

49 Symptoms

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Body Systems

Symptoms related to this disease may affect different systems of the body. Use the 'Filter and Sort' function to learn more about which body system(s) are affected by this disease and their associated symptom(s).

Causes

What Causes This Disease?

Genetic Changes

Advocacy and Support Groups

How Can Patient Organizations Help?

Patient organizations can help patients and families connect. They build public awareness of the disease and are a driving force behind research to improve patients' lives. They may offer online and in-person resources to help people live well with their disease. Many collaborate with medical experts and researchers.

Services of patient organizations differ, but may include:

  • Ways to connect to others and share personal stories
  • Easy-to-read information
  • Up-to-date treatment and research information
  • Patient registries
  • Lists of specialists or specialty centers
  • Financial aid and travel resources

Please note: GARD provides organizations for informational purposes only and not as an endorsement of their services. Please contact an organization directly if you have questions about the information or resources it provides.

Patient Organizations

8 Organizations

Organization Name

Who They Serve

Helpful Links

Country

People With

Monosomy 22q13.3

Helpful Links
Country

United States

People With

Monosomy 22q13.3

Helpful Links
Country

United States

People With

Monosomy 22q13.3

Helpful Links
Country

United States

People With

Monosomy 22q13.3

Helpful Links
Country

United Kingdom

People With

Rare Diseases

Helpful Links
Country

United States

People With

Rare Diseases

Helpful Links
Country

United States

People With

Rare Diseases

Helpful Links
Country

United States

People With

Rare Diseases

Helpful Links
Country

United States

Participating in Clinical Studies

Clinical studies are part of clinical research and at the heart of all medical advances, including rare diseases. Participating in research helps researchers ultimately uncover better ways to treat, prevent, diagnose, and understand human diseases.

What Are Clinical Studies?

  1. Clinical trials determine if a new test or treatment for a disease is effective and safe by comparing groups receiving different tests/treatments.
  2. Observational studies involve recording changes over time among a specific group of people in their natural settings.
Learn more about clinical trials from this U.S. Food & Drug Administration webpage.

Why Participate in Clinical Studies?

Join the All of Us Research Program!

What if There Are No Available Clinical Studies?

What Are Clinical Studies?

Clinical studies are medical research involving people as participants. There are two main types of clinical studies:
  1. Clinical trials determine if a new test or treatment for a disease is effective and safe by comparing groups receiving different tests/treatments.
  2. Observational studies involve recording changes over time among a specific group of people in their natural settings.
Learn more about clinical trials from this U.S. Food & Drug Administration webpage.
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Why Participate in Clinical Studies?

People participate in clinical trials for many reasons. People with a disease may participate to receive the newest possible treatment and additional care from clinical study staff as well as to help others living with the same or similar disease. Healthy volunteers may participate to help others and to contribute to moving science forward.

To find the right clinical study we recommend you consult your doctors, other trusted medical professionals, and patient organizations. Additionally, you can use ClinicalTrials.gov to search for clinical studies by disease, terms, or location.
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Join the All of Us Research Program!

What if There Are No Available Clinical Studies?

ClinicalTrials.gov, an affiliate of NIH, provides current information on clinical research studies in the United States and abroad. Talk to a trusted doctor before choosing to participate in any clinical study. We recommend checking this site often and searching for studies with related terms/synonyms to improve results.
Please contact GARD if you need help finding additional information or resources on rare diseases, including clinical studies. Note, GARD cannot enroll individuals in clinical studies.
Available toll-free Monday through Friday from 12 pm to 6 pm Eastern Time
(Except: Federal Holidays)
Use the contact form to send your questions to a GARD Information Specialist.

Please allow 2 to 10 business days for us to respond.
ClinicalTrials.gov, an affiliate of NIH, provides current information on clinical research studies in the United States and abroad. Talk to a trusted doctor before choosing to participate in any clinical study. We recommend checking this site often and searching for studies with related terms/synonyms to improve results.
Please contact GARD if you need help finding additional information or resources on rare diseases, including clinical studies. Note, GARD cannot enroll individuals in clinical studies.
Available toll-free Monday through Friday from 12 pm to 6 pm Eastern Time
(Except: Federal Holidays)
Use the contact form to send your questions to a GARD Information Specialist.

Please allow 2 to 10 business days for us to respond.
Getting a Diagnosis

Take steps toward getting a diagnosis by working with your doctor, finding the right specialists, and coordinating medical care.

Last Updated: November 2023