-Is caused by a spontaneous mutation at conception; nothing either parent did caused their child’s condition
-Primarily affects girls due to its location on the X-chromosome, though there are affected boys
-Was only recently discovered in 2014
-Has only been identified in about 300 individuals, however, doctors believe it is the cause of 1 to 3 percent of all intellectual disabilities in females
-Is often misdiagnosed as autism spectrum disorder, cerebral palsy, Rett Syndrome, Dandy Walker Syndrome, or a generic developmentally delayed label
-Is linked to intellectual disabilities, seizures, autism, low muscle tone, abnormalities of the brain, and slower physical developments
-Has a broad spectrum—some children learn to speak in full sentences while others are nonverbal; some individuals run, jump, and even ski while others are unable to walk

Researchers across the globe are now looking at DDX3X syndrome and its effects. Our purpose is to help families and researchers move forward. Learn more about DDX3X research.


Do you think your child could have DDX3X syndrome?
Not all individuals with DDX3X are affected in the same ways, however, the following are common symptoms:

  • Intellectual disability
  • Developmental delays
  • Low muscle tone/hypotonia
  • Difficulty with speech
  • Epilepsy/seizures
  • Movement disorders
  • Abnormalities of the brain
  • Microcephaly


DDX3X syndrome can be found using Whole Exome Sequencing (WES)—a test that sequences the protein-coding regions of the 20,000 genes in an individual, as well as more targeted panel analysis, such as the Congenital Hypotonia Xpanded Panel offered by Gene Dx, which targets the specific phenotype-driven gene list for hypotonia/low muscle tone. WES and more targeted panel testing are becoming more readily available, affordable, and common for the diagnosis of conditions believed to have a genetic basis.

GeneDx, a Maryland-based genetic testing company, was one of the first laboratories to identify the DDX3X gene and the association between alterations in this gene and intellectual disabilities. It is one of several clinical laboratories that does WES and panel testing based on specific conditions, such as hypotonia. Testing by WES or a specific gene panel must be requested by a doctor and the results sent to a medical facility. Families interested in genetic testing should discuss that option with their doctor, who may recommend genetic counseling and a genetics evaluation to determine if WES or a specific panel test is the appropriate diagnostic test to pursue.

New! Face2Gene is a free search and reference tool used by healthcare professionals to detect and reveal genetic syndromes associated with the appearance or gradual development of distinctive facial characteristics in affected patients. FDNA has developed a technology that analyzes facial photos to identify facial morphology associated with rare diseases. FDNA is collecting data from images of patients with confirmed diagnosis of many different genetic diseases, including DDX3X, to improve this technology further. As more data is collected, the technology learns and becomes more accurate for the benefit of the entire genetic expert community and their patients. Inquire with your genetic counselor to determine if Face2Gene may be a viable option for your child



A series of talks at a DDX3X Family day with speakers including geneticists and genetic counselors

DDX3X Family Day Sessions:

  1. 2019 San Antonio, TX
  2. 2018 Philadelphia, PA
  3. 2017 San Diego, CA
  4. 2016 Chicago, IL
  5. 2015 Strasburg, PA


Since 2015, we have facilitated the acceleration of research on DDX3X gene mutations by increasing the network of researchers from one to twenty and research papers from one to more than thirty. Click here to read the more than thirty research papers currently available on DDX3X.