RecruitingPhase 2NCT06261502
Neurological
Fragile X Syndrome
Also known as FXS, FMRP deficiency, Martin-Bell syndrome, FMR1 CGG repeat expansion
Fragile X syndrome is the most common inherited cause of intellectual disability and the leading single-gene cause of autism spectrum disorder, caused by CGG trinucleotide repeat expansion in the FMR1 gene leading to silencing of FMRP prote
ORPHA:908 ↗Gene FMR1Prevalence 1-5 per 10,000 (Orphanet)Onset ChildhoodX-linked genetic (trinucleotide repeat expansion)
16
studies recruiting now
as of 7 Sept 2026
121
studies registered in total
as of 7 Sept 2026
4
countries with a recruiting site
as of 7 Sept 2026
17 Jun 2026
most recent study posted
among recruiting studies
Recruiting trials
RecruitingPhase 2NCT07209462
Study of MRM-3379 in Male Participants With Fragile X Syndrome (BLOOM)
RecruitingNCT07434037
The Neurocognitive Bases of Trust in Intellectual Disability
RecruitingPhase 2NCT06081348
Sertraline vs. Placebo in the Treatment of Anxiety in Children and AdoLescents With NeurodevelopMental Disorders
RecruitingPhase 2NCT07654114
Safety, Tolerability, and Preliminary Effectiveness of CTH120 in Fragile X Syndrome
Showing the 5 most recently updated recruiting studies, as recorded 7 Sept 2026. Live status on each study page.
See all 16 recruiting studiesWhere recruiting studies are running
Countries with at least one recruiting site among the studies above, 7 Sept 2026. Tap a country to search trials there.
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About Fragile X Syndrome
Fragile X syndrome is the most common inherited cause of intellectual disability and the leading single-gene cause of autism spectrum disorder, caused by CGG trinucleotide repeat expansion in the FMR1 gene leading to silencing of FMRP protein expression. Clinical features include intellectual disability, social anxiety, repetitive behaviors, large ears, macroorchidism in males, and hyperarousal. Females are typically less severely affected. Premutation carriers (55-200 repeats) are at risk for fragile X-associated tremor/ataxia syndrome (FXTAS).
Common clinical features
Intellectual disabilityAutism spectrum featuresSocial anxiety and avoidanceHyperactivityMacroorchidism (males)Large ears and prominent jawSeizures (20-25%)
From Orphanet’s phenotype annotations (CC BY 4.0). Not a complete list.
Treatments being studied
27 in clinical development, from Open Targets (CC BY 4.0). Not medical advice.
Phase 3Baclofen (Baclofen)
Phase 3Zatolmilast
Phase 3Vitamin E (Aquasol e)
Phase 3Cannabidiol (Epidiolex)
Phase 3Arbaclofen Placarbil
Phase 3Arbaclofen
Phase 2/3Mavoglurant
Phase 2Roflumilast (Daliresp)
+ 19 more in development
Before you apply
Things trial teams commonly ask about for Fragile X Syndrome. Not eligibility rules; those are set by each study.
- Full mutation CGG repeat count (>200 repeats) confirmed by Southern blot or PCR is the diagnostic requirement for FXS trials
- Premutation carriers (55-200 repeats) qualify for FXTAS trials — these are distinct populations from full mutation FXS trials
- Cognitive and behavioral endpoints (VABS, SNAP-IV, ABC-C) are standard baseline and outcome assessments
- FMRP-targeting trials (metformin, mGluR5 antagonists) may require washout from prior investigational therapies
Related conditions
Information, not medical advice. Trial listings are shown as recorded on ClinicalTrials.gov; whether any study is right for you is a decision for you and your clinicians, and eligibility is decided by each research team. Disease information from Orphanet (CC BY 4.0).