Definition

Rett syndrome is a developmental nervous system disorder. It primarily affects girls. It is uncommon, but not rare. It occurs in one out of every 10,000-23,000 female births. Boys with the gene defect that causes this disorder are usually stillborn or die shortly after birth.

Rett syndrome can be classified into classic and atypical. This depends on the symptoms.

Many people with Rett syndrome live into adulthood. Most have severe disabilities. While many cannot talk or walk, they usually have a full range of feelings and often communicate through their eyes. People with Rett syndrome usually need daily care throughout their life.

Causes

The majority of cases are caused by nonhereditary mutations in the Rett syndrome gene on one X chromosome. Females have two X chromosomes. Males have one X and one Y chromosome. Males usually die from mutations in the Rett syndrome gene. This is because they lack the second normal X chromosome, which partially protects females.

In Rett syndrome, the mutated gene affects methyl cytosine binding protein 2 (called MECP2). When it is mutated, there is a deficiency of this important protein. This is an area that is still being studied.

Scientists have not discovered why the Rett syndrome gene is susceptible to mutation. They also have not found what factors lead to this genetic damage. There do appear to be some “hot spots” on the gene. These hot spots are more likely to develop mutations. Because Rett syndrome is usually nonhereditary, it does not commonly occur in multiple children within a family.

Risk Factors

There are no known risk factors for Rett syndrome, except being female. The mutation that causes the syndrome appears to be sporadic.

Symptoms

A girl with Rett syndrome will start developing normally. She will smile, move, and pick items up with her fingers. But by 18 months of age, the developmental process seems to stop or reverse itself. The age of onset and the severity of symptoms can vary. There are four stages. Symptoms include:

Stage IV: Late Motor Deterioration Stage

• Age: when stage III ceases, can be anywhere from age 5 to 25
• Duration: up to decades

Symptoms may include:

• Decreased ability to walk
• Muscle weakness or wasting
• Stiffness of muscles
• Spastic movements
• ]]>Scoliosis]]> (curvature of the spine)
• Breathing trouble and seizures often decrease with age
• Puberty usually begins at the expected age

Scoliosis

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Diagnosis

The doctor will:

• Ask about your child’s symptoms and medical history
• Do a physical and neurological exam
• Exclude other disorders, such as autism]]>
• Do genetic testing can often confirm the diagnosis

Ninety-five percent of girls with Rett Syndrome and 50% of those with the atypical form have the MECP2 mutation. But, not everyone with this mutation will have Rett syndrome. Some females may be normal or have only mild symptoms. But, these women can pass the gene to their daughters. The daughters may then be more severely affected.

Some of the motor functions of Rett syndrome are similar to those of autism. Children with autism, who are more often boys, do not maintain person-to-person contact. Most girls with Rett syndrome, though, prefer human contact to focusing on inanimate objects. These differences may give the first clue in diagnosing Rett syndrome.

Aside from genetic testing, the diagnosis is confirmed by comparing the physical and developmental findings with those typically found in Rett syndrome.

Tests may include:

• Blood test—to check for genetic mutation (MECP2)
• ]]>Electroencephalogram]]> (EEG)—a test that records the electrical activity of the brain
• Video-EEG—a test that combines EEG with a video to see if some of the child's movements are caused by seizures

Treatment

There is no cure for Rett syndrome. People with this condition need to be monitored for:

• Skeletal problems
• Heart problems

Treatment aims to control symptoms and includes:

Prevention

There is no way to prevent Rett syndrome. If you have questions about the risk of Rett syndrome in your family, talk to a genetic counselor.