The information for this summary of PHF21A-related syndrome comes from research publications. This is not meant to take the place of medical advice.

Click here for our full PHF21A Gene Guide

The online Gene Guide includes more information about PHF21A such as the chance of having another child with this condition, behavior and development concerns linked to PHF21A-related syndrome or specialists to consider for people with this condition. Share this resource with family members or your clinical providers.

PHF21A-related syndrome is also called intellectual developmental disorder with behavioral abnormalities and craniofacial dysmorphism with or without seizures. For this webpage, we will be using the name PHF21A-related syndrome to encompass the wide range of variants observed in the people identified.

What is PHF21A-Related Syndrome?

PHF21Arelated syndrome happens when there are changes in the PHF21A gene. These changes can keep the gene from working as it should.

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.

Key Role

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


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

  • Developmental delay
  • Intellectual disability
  • Autism
  • Seizures
  • Brain changes seen on magnetic resonance imaging (MRI)
  • Increased weight, height, head size
  • Anxiety
  • Attention deficit hyperactivity disorder, or ADHD

How many people have PHF21A-related syndrome?

As of 2024, at least 32 people with PHF21A-related syndrome have been identified in a medical clinic. The first case of PHF21A-related syndrome was described in 2012.

In Potocki-Shaffer syndrome, people are missing a large segment of DNA that includes the PHF21A gene. Potocki-Shaffer syndrome is more common than PHF21A-related syndrome, but it is also very rare.


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.

There is currently no GeneReviews for PHF21A-related syndrome.


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!