What is Rett syndrome?
Rett syndrome is a neurodevelopmental disorder. It is characterized by typical early growth and development, which is then followed by:
- A slowing of development
- Loss of mobility or function in the hands
- Distinctive hand movements
- Slowed brain and head growth
- Problems with walking, walking on the toes, or a wide-based gait
- Cognitive problems
- Digestive problems
- Trouble performing motor functions, including speaking and controlling eye movements (apraxia)
- Breathing difficulties while awake, including breath holding, hyperventilation, and swallowing air
Other symptoms may include sleep problems, teeth grinding, and difficulty chewing.
Age of onset, severity of symptoms, and how Rett syndrome progresses varies from child to child. While children who go on to develop Rett syndrome grow and develop as expected initially, there are often subtle differences even in early infancy and toddlerhood, such as:
- Loss of muscle tone (hypotonia)
- Difficulty feeding
- Jerkiness in limb movements
- Problems crawling or walking
- Less eye contact
The loss of functional use of the hands is followed by compulsive hand movements such as hand wringing. The onset of these symptoms is sometimes sudden.
Who is more likely to get Rett syndrome?
Any racial or ethnic group can experience Rett syndrome. Rett syndrome most commonly affects girls, although boys are also (rarely) affected. Boys are usually more severely affected than girls.
Nearly all cases of Rett syndrome are caused by a mutation in the methyl CpG binding protein 2, or MECP2 (pronounced meck-pea-two) gene. The MECP2 gene contains instructions for the synthesis of a protein called methyl cytosine binding protein 2 (MeCP2), which is needed for brain development and acts as one of the many biochemical switches that activate and deactivate gene functions. Because theMECP2 gene does not function properly in individuals with Rett syndrome, they may have too little MeCP2, or the MeCP2 they do have doesn’t work properly.
Not everyone who has an MECP2 mutation has Rett syndrome. Scientists believe some cases may be caused by partial gene deletions, mutations in other parts of the MECP2 gene, or additional genes that have not yet been identified. Genetic and environmental factors can contribute to differences in the severity and types of symptoms found in individuals with Rett syndrome. Those may include: where the MECP2 mutation is located in the gene, how the individuals’ sex chromosomes interact, and other genes can make the symptoms worse or protect from the effects of the mutation.
Although Rett syndrome is a genetic disorder, less than 1% of recorded cases are passed from one generation to the next. Most cases are spontaneous, which means the mutation occurs randomly. However, in some families of individuals affected by Rett syndrome, other family members have a mutation in the MECP2 gene. Families that already have an identified MECP2 mutation can get genetic testing to identify if they are carriers of the disorder.
How is Rett syndrome diagnosed and treated?
Diagnosing Rett syndrome
Doctors diagnose Rett syndrome by observing signs and symptoms during the child's early growth and development and conducting ongoing evaluations of the child's physical and neurological status. Scientists have developed a genetic test to find MECP2 mutations to complement observations and diagnosis by doctors. To confirm a diagnosis of Rett syndrome, families should consult a pediatric neurologist, clinical geneticist, or developmental pediatrician.
Treating Rett syndrome
While there is no cure for Rett syndrome, in 2023, the U.S. Food and Drug Administration (FDA) approved a new drug, Trofinetide, to treat Rett syndrome in children age two and older. Trofinetide works by reducing swelling in the brain, increasing the amount of a protective protein in the brain, and stopping some cells from becoming too active.
Other treatments focus on treating specific symptoms or behaviors seen in Rett syndrome. Medication can help with breathing and movement problems and seizures.
Individuals affected by Rett syndrome should be regularly monitored for scoliosis (curving in the spine) and heart problem. Occupational therapy may help children develop skills needed for everyday activities like dressing, eating, and drawing, while physical therapy and water therapy (hydrotherapy) can help with mobility.
Some children may require special equipment and aids like spinal braces, splints for their hands and wrists, and nutritional support to help them maintain adequate weight. Children with Rett syndrome may need extra help with school and social support.
Many individuals with Rett syndrome live into middle age and beyond, despite the symptoms. Because the disorder is rare, very little is known about long-term prognosis and life expectancy.
What are the latest updates on Rett syndrome?
The National Institutes of Health (NIH), including NINDS and others, supports research on Rett syndrome. Understanding the cause is necessary for developing new therapies to manage specific symptoms, as well as improving diagnostic tools. The discovery of MECP2 in 1999 provides a basis for further genetic studies and enables the use of recently developed animal models such as transgenic mice which are deficient in MECP2. These models have neurologic abnormalities that can be reversed by activating the MECP2 gene later in life.
Scientists are studying mutations in the MECP2 gene of individuals with Rett syndrome to learn about MeCP2 protein function and dysfunction. Information from this study will increase our understanding of the disorder and may lead to new therapies. Other research aims at identifying molecular pathways that are affected, developing animal models of the disorder, and early-stage therapy development.
Some researchers suggest that the specific type of mutation in the MECP2 gene affects the severity of symptoms of Rett syndrome. Studies are underway to understand the mutations and genes contribute to the varied symptoms and severity of this disorder. One NIH-funded natural history study also should provide new information about these topics.
Scientists know that lack of a properly functioning MeCP2 protein disturbs the function of mature brain cells, but they do not know the exact mechanisms by which this happens. Investigators are trying to find other genetic switches that operate in a similar way to the MeCP2 protein. Once they discover how the protein works and locate similar switches, they may devise therapies that can substitute for the malfunctioning switch. Another outcome might involve manipulating other biochemical pathways to compensate for the malfunctioning MECP2 gene, thereby preventing progression of the disorder. Early-stage clinical trials on gene therapy for Rett syndrome are underway.
Researchers also are trying to find other genes that may be involved in Rett syndrome. Some studies have helped to narrow the search for these genes, but much is still unknown about how these genes may cause or contribute to the disorder.
How can I or my loved one help improve care for people with Rett syndrome?
Consider participating in a clinical trial so clinicians and scientists can learn more about Rett syndrome and related disorders. Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.
All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.
Where can I find more information about Rett syndrome?
Information may be available from the following organizations:
Genetic and Rare Diseases (GARD) Information Center
International Rett Syndrome Foundation
Phone: 513-874-1298 or 800-818-7388
National Institute of Child Health and Human Development (NICHD)