Below is a summary for the PHF21A gene observed in research publications. This is not meant to take the place of medical advice. Click HERE for the full gene guide, which includes more information, such as chance of having another child with this condition, or specialists to consider for people with this condition.

What is PHF21A-Related Syndrome?

PHF21A-related syndrome happens when there are changes to the PHF21A gene. These changes can keep the gene from working as it should.

Key Role

The PHF21A gene helps to control other genes and is important for the development of the brain.


Because the PHF21A gene is important in brain development, many people who have PHF21A-related syndrome have:

  • Autism
  • Intellectual disability
  • Seizures
  • Increased weight, height, head size

Some people are missing a large segment of DNA that includes the PHF21A gene. This is called Potocki-Shaffer syndrome or 11p11.2-related syndrome, because the missing segment is on part of chromosome 11. Other people have a small change within the PHF21A gene itself. People who have these different syndromes have symptoms that overlap.

Do people who have PHF21A-related syndrome look different?

People who have PHF21A-related syndrome may look different. One study of four people who have the syndrome found that two had flat foreheads and two had large heads.

How many people have PHF21A-related syndrome?

As of 2019, doctors had found fewer than 10 people in the world with changes in just the PHF21A gene. Potocki-Shaffer syndrome is more common, but also very rare. In Potocki-Shaffer syndrome, people are missing a large segment of DNA that includes PHF21A. The first case of PHF21A-related syndrome was described in 2012. Scientists expect to find more people who have the syndrome as access to genetic testing improves.


4 out of 4 had a speech delay.
4 out of 4 had some degree of intellectual disability.


1 out of 3 had autism.
1 out of 3 seem to require lots of sleep.




3 out of 3 had larger than average weight, height, and head size.


3 out of 4 had low muscle tone. 1 out of 4 had seizures.


Support Resources




GeneReviews are a great resource to bring to your child’s clinicians. These publications provide a summary of current research on genetic conditions and information on ongoing care.

PHF21A is sometimes affected in a chromosome 11 deletion. The GeneReviews for Enlarged Parietal Foramina describes this genetic change.


Research Article Summaries

We currently do not have any article summaries for PHF21A, but we add resources to our website as they become available.

The information available about PHF21A is limited, and families and doctors share a critical need for more information. As we learn more from children who have this gene change, we expect our list of resources and information to grow.

Full versions of published research articles can be found on PubMed. PubMed is a National Institutes of Health (NIH) online database that is free. It has a collection of both medical and scientific research articles. A PubMed search for PHF21A articles can be found here.

You can also visit the Simons Foundation’s SFARI Gene website to see information for researchers about this gene.


Research Opportunities

Simons Searchlight

Help the Simons Searchlight team learn more about PHF21A genetic changes by taking part in our research. You can learn more about the project and sign up here.

External Research Opportunity: FaceMatch

FaceMatch is a platform that helps parents and doctors contribute to an international secure image database of both undiagnosed and diagnosed children across the globe. *This study is not affiliated with Simons Searchlight. Learn more about FaceMatch.


Family Stories

We do not currently have any stories from PHF21A families.

Click here to share your family’s story!