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Classic Rett syndrome

Classic Rett syndrome is a progressive neurodevelopmental disorder primarily affecting girls. Is it characterized by:

  • Normal psychomotor development during the first 6-18 months, followed by a short period of developmental stagnation, then a rapid regression of language and motor skills, followed by long term stability.
    • Abnormal muscle tone, which may lead to muscle spasms and abnormal posture
    • Foot and hand deformities
    • Repetitive, stereotypic hand movements that replace purposeful hand use
    • Fits of screaming and inconsolable crying
    • Autistic features
    • Panic-like attacks
    • Teeth-grinding
    • Irregular breathing
    • Instability when walking or abnormal gait
    • Tremors and seizures (90%)
      • Generalized tonic clonic seizures and partial complex seizures are most common
    • Acquired microcephaly (small head size)
    • Scoliosis/kyphosis (80%)
    • Diminished response to pain
    • Small, cold hands and feet
    • Bowel dysmotility, constipation
    • Unusual eye movements
      • Intense staring
      • Blinking
      • Closing one eye at a time
    • Reduced bone mass (74%)
      • Increased risk of fractures can occur
        • Ambulatory individuals have better bone density than non-ambulatory individuals
    • Growth failure and wasting that worsens with age (80-90%)
      • May be caused in part by poor food intake

Atypical or variant Rett syndrome

  • Intellectual disability with abnormal increase in muscle tone, muscle stiffness, or muscle tremors
  • Age when symptoms first appear varies 
  • Mild learning disability (rare)
  • Autism (rare)

Affected males

  • In males, severe neonatal brain disease occurs, usually resulting in death before age 2