Tests and diagnosis

By Mayo Clinic Staff

Diagnosing Rett syndrome involves careful observation of your child's growth and development and answering questions about medical and family history. The diagnosis is usually considered when slowing of head growth is noticed.

For a diagnosis of Rett syndrome, other conditions with similar symptoms must be ruled out.

Evaluating other causes for the symptoms

Because Rett syndrome is rare, your child may have certain tests to identify if other conditions are causing some of the same symptoms as Rett syndrome. Some of these conditions include:

  • Other genetic disorders
  • Autism
  • Cerebral palsy
  • Hearing or vision problems
  • Metabolic disorders, such as phenylketonuria (PKU)
  • Disorders that cause the brain or body to break down (degenerative disorders)
  • Brain disorders caused by trauma or infection
  • Brain damage before birth (prenatal)

What tests your child needs depends on specific signs and symptoms. Tests may include:

  • Blood tests
  • Urine tests
  • Imaging tests such as magnetic resonance imaging (MRI) or computerized tomography (CT) scans
  • Hearing tests
  • Eye and vision exams
  • Brain activity tests (electroencephalograms, also called EEGs)

Criteria for diagnosis

A diagnosis of classic Rett syndrome includes these core symptoms:

  • Partial or complete loss of purposeful hand skills
  • Partial or complete loss of spoken language
  • Walking abnormalities, such as problems walking or not being able to walk
  • Repetitive purposeless hand movements, such as hand wringing, squeezing, clapping or tapping, putting hands in the mouth, or washing and rubbing movements

Additional typical symptoms can support the diagnosis.

Diagnostic criteria for atypical or variant Rett syndromes may vary slightly, but the symptoms are the same, with varying degrees of severity.

Genetic testing

If your child's doctor suspects Rett syndrome after evaluation, he or she may recommend a genetic test (DNA analysis) to confirm the diagnosis. The test requires drawing a small amount of blood from a vein in the arm. The blood is then sent to a lab, where technicians examine your child's DNA for abnormalities and clues as to the cause and severity of the disorder.

Sept. 17, 2015