Testing & Diagnosis for Rett Syndrome in Children

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Contact the Rett Syndrome Program

At Boston Children’s Hospital, we know that the first step in treating your child’s Rett syndrome is to form an accurate and complete diagnosis. Our specialists are leaders in evaluating and diagnosing children with Rett syndrome and related conditions.

How is Rett syndrome diagnosed?

A genetic test that detects the MECP2 mutation on the child’s X chromosome has been developed to confirm the clinical diagnosis of the disorder. Of all cases of clinically diagnosed Rett syndrome, between 80-97% are found to have mutations in the MECP2 gene (a “positive” genetic test). However, even if a MECP2 mutation is identified, the child may not be diagnosed with Rett syndrome if they do not fit the diagnostic criteria. For this reason, a diagnosis of Rett syndrome is also made through observing signs and symptoms during a girl’s early development.

Criteria for diagnosing Rett syndrome

The MECP2 gene mutation involved in Rett syndrome is also seen with other disorders and can often be misdiagnosed and mistaken for cerebral palsy, autism or non-specific developmental delay. To avoid misdiagnosis, a pediatric neurologist or developmental pediatrician will use a set of highly specific clinical criteria to diagnose Rett syndrome.

The guidelines are divided into three types of clinical criteria: essential, supportive and exclusion.

Essential criteria

Essential criteria refers to symptoms that must be present for a diagnosis of Rett syndrome to be made. Some of the essential criteria for diagnosing Rett syndrome include:

  • a period of normal development until between 6 to 18 months
  • repetitive hand movements including hand washing, hand wringing and hand clasping
  • a normal head circumference at birth followed by a slowing of the rate of head growth with age (starting between the time a child is 6 months and 4 years old)
  • significantly impaired expressive and receptive language
  • shakiness of the torso, which also may involve the limbs, particularly when the child is upset or agitated
  • unsteady, wide-based, stiff-legged gait and sometimes toe walking

Supportive criteria

Supportive criteria describes symptoms that are not necessary for a diagnosis of Rett syndrome but may be seen in some people with the disorder. A girl who meets supportive criteria but no essential criteria does not have Rett syndrome.  Supportive criteria include the following:

  • seizures
  • breathing irregularities such as apnea, hyperventilation and air swallowing
  • abnormal sleep patterns and irritability
  • muscle rigidity or spasticity
  • irritability or agitation
  • electroencephalogram (EEG) abnormalities
  • scoliosis (curvature of the spine)
  • chewing and/or swallowing difficulties
  • teeth-grinding
  • decreased body fat and muscle mass
  • poor circulation of the lower extremities with cold and bluish-red feet and legs
  • decreased mobility with age

Exclusion criteria

Exclusion criteria are various conditions that allow doctors to rule out a diagnosis of Rett syndrome. If a girl has any of the following criteria, she does not have Rett syndrome:

  • neurometabolic disease or other inherited degenerative disorder
  • a neurological disorder resulting from severe infection or head trauma
  • evidence of brain damage acquired after birth
  • vision loss due to retinal disorder or optic atrophy (the loss of some of the fiber of the optic nerve)
  • grossly abnormal psychomotor development in the first six months of life

How does Boston Children’s approach diagnosing Rett syndrome?

At Boston Children’s, we have extensive diagnostic testing capabilities. These tests can help us distinguish Rett syndrome from other neurological and developmental disorders that may have similar symptoms. The diagnostic tests your child might receive include:

  • genetic testing in the Children’s DNA diagnostic laboratory
  • neurophysiological testing
  • brain imaging

Whats the long-term out-look for my child?

Rett syndrome is a disease that will progress slowly throughout your child’s life. However, the speed at which a Rett syndrome progresses in a given child and the severity of symptoms varies. Symptoms will start to become noticeable when your child is between the ages of 1 and 4 and may include repetitive hand movements, loss of spoken language and decreased communication and social interaction.

Depending on the severity of their impairment, some girls may experience improvement in their behavior when they’re between the ages of 2 and 10. During this time, a girl may express an increased interest in surroundings as well as improvement in alertness, attention span and communication skills. Many girls will remain in this plateau stage for the rest of their lives and experience no further decline in communication or motor skills.

Developmental delays also vary from child to child.  Some girls will be able to crawl and sit up independently while other girls won’t. Similarly, some girls may walk independently at some point during their lives while other girls will never gain that ability. Girls who are able to walk might keep that skill for the rest of their lives, while other girls may gradually lose that ability.  Since Rett syndrome follows a progressive course, a girl doesn’t regain these skills once she loses them.

These treatment methods can help manage your daughter’s symptoms, but the course of Rett syndrome will still cause certain skills and abilities to deteriorate. Increased difficulties in performing tasks may develop after the age of 10, and girls who were once able to walk may lose the ability. Muscle weakness and muscle contractions may increase and spinal curvature may become more severe in girls who have scoliosis.

While it is known that Rett syndrome shortens lifespan, not much is known about specific life expectancy rates for girls with Rett syndrome. It generally depends on the age when symptoms first begin and their severity. On average, most girls with the condition survive into their  40s or 50s.

Can Rett syndrome be reversed?
Our clinical trial on IGF-1 as a treatment for Rett syndrome was covered in a December 21, 2010 post on Vector, Boston Children’s research and innovation blog, and in an article, Can drugs improve cognitive deficits in developmental disorders?
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