Below is a summary for the DDX3X gene observed in research publications. This is not meant to take the place of medical advice.

What is DDX3X-related syndrome?

DDX3X-related syndrome happens when there are changes to the DDX3X gene. These changes can keep the gene from working as it should.

DDX3X-related syndrome is also called Snijders Blok type of X-linked syndromic intellectual developmental disorder.

Key Role

DDX3X plays a key role in the growth of the brain.


Many people who have DDX3X-related syndrome have:

  • Intellectual disability/developmental delay
  • Low muscle tone
  • Differences in facial features
  • Movement disorders

Do people who have DDX3X-related syndrome look different?

People who have DDX3X-related syndrome may look different. Appearance can vary and can include some but not all of these features:

  • About 1 in 4 people have a small head
  • About 1 in 4 people have a thin upper lip and large ears

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 DDX3X.


Research Article Summaries

Below, we have summarized research articles about changes in the DDX3X gene. We hope you find this information helpful.

The information available about DDX3X is limited, and families and doctors share a critical need for more information. As we learn more from children who have a change in this gene, we expect this 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 DDX3X articles can be found here.

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


Mutations in DDX3X are a common cause of unexplained intellectual disability with gender-specific effects on Wnt signaling

Original research article by L. Snijders Blok et al. (2015).

Read the abstract here and the Simons Searchlight summary here.


Research Opportunities

Simons Searchlight

Help the Simons Searchlight team learn more about DDX3X genetic changes by taking part in our research. You can learn more about the project and sign up here.

Research into speech & language skills in individuals with DDX3X variants: an international study

Researchers are running a project looking at speech & language in individuals with DDX3X variants. By improving our understanding of speech & language abilities, they hope to improve prognoses, better identify individuals in need of speech therapy, and develop more targeted therapies. *This study is not affiliated with Simons Searchlight. See their flyer 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.

If interested or would like to know more contact; angela.morgan@mcri.edu.au, or geneticsofspeech@mcri.edu.au.


Family Stories

Stories from DDX3X families:

Click here to share your family’s story!