Updated: 10/21/2020

Fragile X Syndrome

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https://upload.medbullets.com/topic/113045/images/mitralinsuff_tee.jpg
https://upload.medbullets.com/topic/113045/images/scoliosis..jpg
Snapshot
  • A 3-year-old boy is brought to a pediatrician. His past medical history is unknown, as this is his first visit to the pediatrician. His mother reports that the family prefers an isolated existence and therefore has not sought medical help. However, she reports being concerned about his learning abilities, as his speech appears delayed compared to his sisters. On physical exam, the boy has a prominently long face, large jaw, and large ears. The pediatrician recommends a genetic test.
Introduction
  • Overview
    • fragile X syndrome is an X-linked dominant disorder characterized by macroorchidism, characteristic facial features, intellectual disability, and miral valve prolapse, caused by trinucleotide repeat (CGG) on the FMR1 gene
  • Epidemiology
    • incidence
      • the most common cause of inherited intellectual disability
    • demographics
      • females have less impairment and less physical features typical of fragile X syndrome
    • risk factors
      • family history
  • Genetics 
    • inheritance pattern
      • X-linked dominant inheritance with variable penetrance
    • mutations
      • gene
        • trinucleotide repeat in FMR1 gene resulting in decreased expression 
          • CGG repeats
  • Associated conditions
    • medical conditions and comorbidities
      • mitral valve prolapse
      • gastroesophageal reflux disease
  • Prognosis
    • life span is normal
Presentation
  • Symptoms
    • common symptoms
      • symptoms and behavioral problems may develop at birth of afterwards
      • characterized by developmental, cognitive, and neuropsychiatric issues
    • developmental          
      • developmental delay in motor, speech, and language skills
    • cognitive
      • low IQ
    • neuropsychiatric
      • autism-like behaviors 
        • hand flapping
        • avoidance of eye contact
      • anxiety
      • behavioral issues
        • aggression
        • attention deficits
        • oppositional
        • tantrums
    • seizure disorders
  • Physical exam 
    • inspection
      • facial features
        • long face
        • large jaw
        • large everted ears
      • pectus excavatum
      • scoliosis
      • protruding chin
      • post-pubertal macroorchidism
      • hyperextensible joints
      • heart murmur or click
        • mitral valve prolapse
Imaging
  • Radiograph
    • indications
      • evaluate for scoliosis
    • findings
      • scoliosis
  • Echocardiograph
    • indications
      • evaluate for mitral valve prolapse
    • findings
      • mitral valve prolapse
Studies
  • DNA testing is diagnostic
    • Southern blot test
    • polymerase chain reaction
Differential
  • Autism spectrum disorder (ASD)
    • key distinguishing factor
      • similar behaviors such as hand flapping and avoidance of eye contact
      • patients with ASD lacks physical features typical of fragile X syndrome
Treatment
  • Treatment is aimed at symptomatic management
  • Lifestyle
    • specialist therapists
      • indications
        • speech and language therapy
        • occupational therapy
        • physical therapy
        • behavioral therapy
  • Medical
    • proton pump inhibitors
      • indications
        • gastroesophageal reflux disease
Complications
  • Recurrent infections
  • Seizure disorders


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