RTT occurs almost always in girls. It may be diagnosed as autism or cerebral palsy.

Most RTT cases are due to a problem in the gene called MECP2. This gene is on the X chromosome. Females have 2 X chromosomes. Even when one chromosome has this defect, the other X chromosome is normal enough for the child to survive.

Males born with this defective gene do not have a second X chromosome to make up for the problem. Therefore, the defect usually results in miscarriage, stillbirth, or very early death.

An infant with RTT usually has normal development for the first 6 to 18 months. Symptoms range from mild to severe.

Symptoms may include:

• Breathing problems, which may get worse with stress. Breathing is usually normal during sleep and abnormal while awake.
• Change in development.
• Excessive saliva and drooling.
• Floppy arms and legs, which is frequently the first sign.
• Intellectual disabilities and learning difficulties.
• Scoliosis.
• Shaky, unsteady, stiff gait or toe walking.
• Seizures.
• Slowing head growth beginning at 5 to 6 months of age.
• Loss of normal sleep patterns.
• Loss of purposeful hand movements: For example, the grasp used to pick up small objects is replaced by repetitive hand motions like hand wringing or constant placement of hands in mouth.
• Loss of social engagement.
• Ongoing, severe constipation and gastroesophageal reflux (GERD).
• Poor circulation that can lead to cold and bluish arms and legs.
• Severe language development problems.

NOTE: Problems with breathing patterns may be the most upsetting and difficult symptom for parents to watch. Why they happen and what to do about them is not well understood. Most experts recommend that parents remain calm through an episode of irregular breathing like breath holding. It may help to remind yourself that normal breathing always returns and that your child will become used to the abnormal breathing pattern.

Genetic testing may be done to look for the gene defect. But, since the defect is not identified in everyone with the disease, the diagnosis of RTT is based on symptoms.

There are several different types of RTT:

• Atypical
• Classical (meets the diagnostic criteria)
• Provisional (some symptoms appear between ages 1 and 3)

RTT is classified as atypical if:

• It begins early (soon after birth) or late (beyond 18 months of age, sometimes as late as 3 or 4 years old)
• Speech and hand skill problems are mild
• If it appears in a boy (very rare)

Treatment may include:

• Help with feeding and diapering
• Methods to treat constipation and GERD
• Physical therapy to help prevent hand problems
• Weight bearing exercises with scoliosis

Supplemental feedings can help with slowed growth. A feeding tube may be needed if the child breathes in (aspirates) food. A diet high in calories and fat combined with feeding tubes can help increase weight and height. Weight gain may improve alertness and social interaction.

Medicines may be used to treat seizures. Supplements may be tried for constipation, alertness, or rigid muscles.

Stem cell therapy, alone or in combination with gene therapy, is another hopeful treatment.

The following groups can provide more information and support for people with Rett syndrome and their families:

• International Rett Syndrome Foundation -- www.rettsyndrome.org
• National Organization for Rare Disorders -- rarediseases.org/rare-diseases/rett-syndrome

The disease slowly gets worse until the teen years. Then, symptoms may improve. For example, seizures or breathing problems tend to lessen in the late teens.

Developmental delays vary. Usually, a child with RTT sits up properly, but may not crawl. For those who do crawl, many do so by scooting on their tummy without using their hands.

Similarly, some children walk independently within the normal age range, while others:

• Are delayed
• Do not learn to walk independently at all
• Do not learn to walk until late childhood or early adolescence

For those children who do learn to walk at the normal time, some keep that ability for their lifetime, while other children lose the skill.

Life expectancies are not well studied, although survival at least until the mid-20s is likely. The average life expectancy for girls may be mid-40s. Death is often related to seizure, aspiration pneumonia, malnutrition, and accidents.

Contact your health care provider if you:

• Have any concerns about your child's development
• Notice a lack of normal development with motor or language skills in your child
• Think your child has a health problem that needs treatment

RTT; Scoliosis - Rett syndrome; Intellectual disability - Rett syndrome

Kwon JM. Neurodegenerative disorders of childhood. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 617.

Mink JW. Congenital, developmental, and neurocutaneous disorders. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 389.

Updated by: Evelyn O. Berman, MD, Assistant Professor of Neurology and Pediatrics at University of Rochester, Rochester, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.