Rett Syndrome | Testing and Diagnosis

How is Rett syndrome diagnosed?

Rett syndrome is diagnosed by a physical exam and detailed information about the child’s development and medical history. Key features of a Rett syndrome diagnosis include loss of normal hand use, loss of spoken language, trouble walking, and abnormal hand movements such as hand wringing or clapping.

Your child’s doctor may also order a genetic DNA blood test to support the diagnosis of Rett syndrome. This test may detect a disease-causing change within the MECP2 gene. Most people with a clinical diagnosis of Rett syndrome (80-97 percent) have a change in this gene.

However, even if a MECP2 variation is found, the child may not be diagnosed with Rett syndrome if he or she doesn’t fit the clinical diagnostic criteria. For this reason, Rett syndrome is diagnosed by observing signs and symptoms during early development.

Criteria for diagnosing Rett syndrome

The guidelines for diagnosing Rett syndrome are divided into three types: essential, supportive and exclusion.

Essential criteria

Essential criteria include symptoms that must be present for a child to be diagnosed with Rett syndrome. The essential criteria include:

  • a period of normal development until between 6 to 18 months followed by a loss of skills, then recovery or stabilization of skills
  • partial or complete loss of purposeful hand skills
  • partial or complete loss of spoken language
  • dyspraxic gait (often an unsteady, wide-based and stiff-legged gait)
  • repetitive hand movements (such as hand wringing or squeezing, clapping or tapping, or hand mouthing movements)

Supportive criteria

These include symptoms that are not necessary for a diagnosis of classic Rett syndrome but are often present in people with the disorder. A child who has supportive criteria, but no essential criteria does not have Rett syndrome. Supportive criteria include the following:

  • breathing irregularities while awake, such as apnea, hyperventilation and air swallowing
  • teeth-grinding
  • abnormal sleep patterns
  • abnormal muscle tone (hypotonia, rigidity or spasticity)
  • poor circulation in the hands and feet, with cold and bluish to red hands and feet
  • scoliosis or kyphosis (curvature of the spine)
  • delayed growth
  • small hands and feet
  • inappropriate laughing or screaming spells
  • reduced response to pain
  • intense eye communication or “eye pointing”

Exclusion criteria

Exclusion criteria allow doctors to rule out a diagnosis of Rett syndrome. A child with any of the following criteria does not have classic Rett syndrome:

  • a neurometabolic disease or other inherited degenerative disorder
  • a neurological disorder resulting from severe infection or head trauma
  • evidence of brain damage acquired after birth
  • grossly abnormal development in the first six months of life

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