Medical Research

Using CBD Gel to Treat Fragile X Syndrome

Loren DeVito, PhD
Written by Loren DeVito, PhD
Promising results from a Phase 2 clinical trial

While many people benefit from the use of topical cannabis for skin conditions or arthritis, children with a rare genetic condition may also soon receive benefit from transdermal cannabis as well. A clinical trial of a cannabinoid (CBD) gel was found to be effective in treating behavioral symptoms associated with a condition called Fragile X Syndrome. [1]

People with Fragile X Syndrome have mild or moderate intellectual disability, prominent facial features, delayed motor and language development, and social impairments like those seen in autism, among other symptoms like epilepsy and cardiovascular conditions. [2]

This condition is caused by dysfunction of a gene called FMR1. This gene is broken or “fragile” in a certain part of the X chromosome, for which the disease is named and caused upon this breakage. Since FMR1 produces the protein FMRP that is vital to cell function, damage to this gene affects many different systems in the body. [2]

Several approaches can help people manage their symptoms, including special education, speech/motor therapy, and behavior training. [2] But, to date, there are no therapies that can slow or stop this condition. However, there are many different compounds currently in clinical testing — including CBD.

But why CBD?

Research has indicated that Fragile X Syndrome is associated with disruption of the endocannabinoid system (ECS). In fact, a pre-clinical study showed that targeting the ECS might improve cognitive impairment and other symptoms associated with the disease. [3] This evidence, in addition to studies demonstrating CBD’s effectiveness in treating anxiety, motivated researchers to pursue the link between the ECS and Fragile X Syndrome using a CBD-based therapy. [4]

Last year, Zynerba Pharmaceuticals presented data on results from their Phase 2 study of a transdermal CBD gel to treat children with Fragile X Syndrome called the FAB-C (Treatment of Fragile X Syndrome Anxiety and Behavioral Challenges with CBD) trial, which took place in Australia. In this trial, researchers treated 5 girls and 15 boys 6-17 years old with the CBD compound (called ZYN002) for 12 weeks; 13 of those children continued with the trial for another 24 months. [1]

Children treated with ZYN002 saw significant improvements in anxiety, compulsive and manic/hyperactive behavior, and other types of social behaviors compared to before they started treatment. Additionally, the treatment was well tolerated, meaning that it didn’t cause any significant side effects. [1]

While this was a small trial of only 20 patients, the results are very promising. In fact, Zynerba has initiated a Phase 3 trial to further evaluate the safety and efficacy of ZYN002 in a larger group of patients. The use of CBD as a transdermal gel may have led to its efficacy, as topicals bypass the digestive system and allow for direct absorption into the blood. This method of administration could also minimize side effects and allow for the use of a lower dose. [5]

“These data are consistent and compelling, and suggest that ZYN002 may have a clinically meaningful and durable effect on the most common observable behaviors associated with childhood and adolescent Fragile X syndrome,” said Dr. Honey Heussler of the University of Queensland who led the trial in a press release.

The FDA agrees with this statement as well, since they granted the treatment orphan drug designation. This means that the FDA will help the company develop the treatment and hopefully get it to patients faster.

Learn more about the Phase 3 trial, called CONNECT-X, which is currently recruiting patients.



  1. Heussler, H., et al., “Transdermal Cannabidiol (CBD) Gel for the Treatment of Fragile X Syndrome (FXS).” Presented at: 16th NFXF International Fragile X Conference; July 12, 2018; Cincinnati, Ohio. Available at: Accessed June 5, 2019.
  1. Ciaccio, C., et al. “Fragile X Syndrome: A Review of Clinical and Molecular Diagnoses.” Ital J Pediatr. vol.43, no.1, 2017, pp. 1-12.
  2. Busquets-Garcia, A., et al. “Targeting the Endocannabinoid System in the Treatment of Fragile X Syndrome.” Nat Med. vol.19, no.5, 2013, pp. 603-607.
  3. Blessing, E.M., et al., “Cannabidiol as a Potential Treatment for Anxiety Disorders.” Neurotherapeutics. vol.12, no.4, 2015, pp. 825-836.
  4. Bonn-Miller, et al. “US Patent 10,213,390 B1: Treatment of Fragile X with Cannabidiol.” Available at: Accessed: June 5, 2019.


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Loren DeVito, PhD

Loren DeVito, PhD

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