What are the symptoms of Fragile X Syndrome (FXS)?

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From the Guidelines

Fragile X syndrome presents with a range of symptoms that vary in severity, including specific cognitive deficits, characteristic physical features, and behaviors, as outlined in the 2013 guidelines for fragile X testing 1. The symptoms of Fragile X Syndrome (FXS) can be categorized into several key areas, including:

  • Physical symptoms: such as a long face, large ears, flat feet, and hyperextensible joints
  • Intellectual disability: present in most affected males and about one-third of females, ranging from mild to severe
  • Speech and language delays: common, with repetitive speech patterns often observed
  • Behavioral symptoms: including attention deficit hyperactivity disorder (ADHD), anxiety, hand flapping, poor eye contact, and sensory sensitivities
  • Medical issues: such as seizures, recurrent ear infections, and mitral valve prolapse According to the guidelines, individuals with the premutation may also experience learning difficulties, emotional problems, or even intellectual disability, particularly those with high repeat sizes (>100 repeats) 1. It is essential to note that females with premutations are at a ~20% risk for premature ovarian insufficiency (POI), while older males and females with premutations are at risk for FXTAS, a late-onset, progressive development of intention tremor and ataxia often accompanied by progressive cognitive and behavioral difficulties 1. Early diagnosis and intervention with speech therapy, occupational therapy, and behavioral therapy can help manage symptoms and improve outcomes in individuals with Fragile X syndrome.

From the Research

Symptoms of Fragile X Syndrome (FXS)

The symptoms of FXS can be categorized into physical, cognitive, and behavioral features. Some of the common symptoms include:

  • Hypersensitivity to stimuli
  • Overarousability
  • Inattention
  • Hyperactivity
  • Explosive and aggressive behavior (mostly in men) 2
  • Social anxiety
  • Other anxiety disorders
  • Depression
  • Impulse control disorder
  • Mood disorders

Behavioral Profile

The behavioral profile of individuals with FXS depends on gender and the molecular status of the mutation. Features of the behavioral profile include:

  • Attention-deficit/hyperactivity disorder symptoms
  • Irritability/agitation
  • Aggression
  • Self-injury
  • Obsessive-compulsive disorder (OCD)
  • Mood swings 3

Psychiatric Disorders

Individuals with FXS are at risk of developing various psychiatric disorders, including:

  • Anxiety disorders
  • Attention deficit hyperactivity disorder (ADHD)
  • Autism spectrum disorder (ASD)
  • Mood instability
  • Aggression 2, 3, 4

Treatment

While there is no specific treatment for FXS, various medications can be used to manage the symptoms. These include:

  • Stimulants for hyperactivity
  • Alpha(2)-adrenoceptor agonists and beta-adrenoceptor antagonists for overarousability, impulsivity, and aggressiveness
  • Selective serotonin reuptake inhibitors (SSRIs) for anxiety, impulsivity, and irritability
  • Antipsychotics for psychotic disorders and severe aggressive behaviors
  • Mood stabilizers for mood dysregulation or mood disorders 2, 3, 5

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Psychotropic Drug Treatment Patterns in Persons with Fragile X Syndrome.

Journal of child and adolescent psychopharmacology, 2021

Research

[Medical treatment of fragile X syndrome].

Revista de neurologia, 2001

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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