How is Rett Syndrome Diagnosed?

What is Rett syndrome?

  • Did your child have an apparently normal prenatal and perinatal history?
  • Was her motor development normal?
  • Was her head circumference at birth normal?
  • Did she lose purposeful hand skills between 18 months and 30 months?
  • Does she have hand movements like wringing, clapping, mouthing or rubbing?
  • Has she withdrawn socially?
  • Has she forgotten skills?
  • Can a boy have Rett?

The diagnostic criteria for Rett syndrome include:

  • apparently normal prenatal and perinatal history
  • psychomotor development largely normal through the first six months or may be delayed from birth
  • normal head circumference at birth
  • postnatal deceleration of head growth in the majority
  • loss of achieved purposeful hand skill between ages 1/2-21/2 years
  • stereotypic hand movements such as hand wringing/squeezing, clapping/tapping, mouthing and washing/rubbing automatisms

And also possibly:

  • awake disturbances of breathing (hyperventilation, breath-holding, forced expulsion of air or saliva, air swallowing)
  • teeth grinding (bruxism)
  • impaired sleep pattern from early infancy
  • abnormal muscle tone successively associated with muscle wasting and dystonia
  • peripheral vasomotor disturbances (cold, blue hands and feet)
  • scoliosis/kyphosis progressing through childhood
  • growth retardation
  • hypotrophic (small) feet; small, thin hands

But not:

  • enlarged organs or other signs of storage disease
  • retinopathy, optic atrophy, or cataract
  • evidence of brain damage before or after birth
  • existence of identifiable metabolic or other progressive neurological disorder
  • acquired neurological disorder resulting from severe infections or head trauma

Clinical Criteria

Rett syndrome is most often misdiagnosed as autism, cerebral palsy, or non-specific developmental delay. In the past, making the correct diagnosis called not only for a long list of diagnostic tests and procedures to rule out other disorders, but it also took from months to years waiting to confirm the diagnosis as new symptoms appeared over time. 

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Genetic Testing

Mutations in another gene on the X-chromosome known as CDKL5 (cyclin-dependent kinase-like 5) can cause an atypical form of Rett Syndrome called the early-onset seizure variant. These individuals have generally tested negative for a MECP2 mutation. Not everyone with a CDKL5 mutation appears as atypical RTT.  

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