Rett syndrome (RTT) is a rare genetic condition that results in certain mental and physical disabilities. It tends to only affect females.

RTT develops due to a mutation in one of the genes on the X chromosome. The gene in question is the methyl CpG binding protein 2 (MECP2) gene.

RTT is very rare and occurs in around 1 in every 10,000–15,000 live female births. There are four stages of RTT, and the first stage typically begins between the ages of 6 and 18 months.

Keep reading to learn more about RTT, including the symptoms, treatments, and outlook for this rare condition.

RTT is a neurological condition. An infant with RTT will usually have normal early growth at the beginning of life, followed by a number of symptoms that develop in stages.

Infants with RTT may have one or more of these common symptoms:

  • slowing of development
  • loss of purposeful use of the hands
  • distinctive hand movements
  • slowed brain growth
  • slowed head growth
  • difficulty walking
  • seizures
  • intellectual disability

The condition primarily affects females. This is because the MECP2 gene is on the X chromosome. Females have two X chromosomes, while males only have one X chromosome. In females, one of each two X chromosomes is inactive in each cell.

Which one is active is random, which is why the severity of RTT varies so much from person to person.

In males, there is only one X chromosome, so RTT is typically lethal to the male fetus. If the fetus does survive to birth, the infant will likely have a severe case of RTT and likely die early in life.

RTT is almost always due to a mutation in the MECP2 gene. This gene is located on the X chromosome. Scientists discovered this gene in 1999, and they believe its role is to control the functions of many other genes.

Mutations in the CDKL5 and FOXG1 genes can also cause RTT, but there will be slightly different clinical patterns when this is the case.

According to one study, despite the scientific progress that researchers have made since the discovery of RTT, the exact way in which these mutations cause RTT is largely unknown.

Some infants with RTT have a more severe case than others. The age at which a child begins to show symptoms of RTT also varies on a case-by-case basis.

There are four recognized stages of RTT. The sections below will look at each of these in more detail.

Stage 1: Early onset

This stage typically begins at 6–18 months old. During this early stage, the infant may show less eye contact and may also display reduced interest in their toys.

A child with RTT may also show delays in motor skill development, such as sitting or crawling. Other symptoms that can appear during this stage include hand-wringing and a decrease in head growth. However, the decrease in head growth is rarely enough to be noticeable this early.

Stage 1 often lasts for several months, but it can last for a year or more. The changes occur slowly and can be subtle, meaning that these early symptoms may go unnoticed.

Stage 2: Rapid destructive stage

The second stage of RTT often begins between the ages of 1 and 4 years old.

During this stage, the symptoms may develop rapidly or gradually. The infant will develop severe issues with communication, language, memory, movement, and other brain functions.

Some symptoms that may develop during stage 2 include:

  • loss of purposeful hand skills
  • loss of spoken language
  • characteristic hand movements, such as wringing, clapping, washing, or tapping
  • repeatedly moving the hands to the mouth
  • clasping the hands behind the back
  • breathing irregularities
  • loss of social interaction
  • loss of communication
  • unsteady walking
  • slowed head growth

Depending on the severity of RTT, not all of the above symptoms may be present during stage 2.

This second stage can last from 2 months to a few years.

Stage 3: Plateau

The third stage of RTT usually begins between the ages of 2 and 10 years old. The child’s behavior will often improve during this stage. This may lead to them being less irritable and crying less.

During stage 3, a child may also be more interested in their surroundings. They may be more alert, have a longer attention span, and show improved communication skills.

However, they may also develop motor problems and start to have seizures, which may become more common.

They may also develop irregular breathing patterns, such as shallow breathing followed by rapid breathing, deep breathing, or holding their breath.

This stage may last for many years. Females will often remain in this stage for most of their lives.

Stage 4: Motor deterioration

The final stage of RTT can last for years or even decades. The main symptoms of stage 4 RTT can include:

  • reduced mobility
  • losing the ability to walk
  • development of a curve of the spine, known as scoliosis
  • muscle weakness and abnormal stiffness

The person’s communication, language, and hand skills generally do not tend to get worse during stage 4.

A doctor will diagnose RTT by visually observing a child’s behavior and symptoms. This will often occur during the child’s early growth and development.

A doctor will then continue to carry out regular checks on the child’s physical and neurological status.

There is also a genetic test that can diagnose RTT. A doctor will carry out a blood test, and a laboratory will analyze the sample. The test looks for the mutated MECP2 gene and will come back either positive or negative.

There is currently no cure for RTT, and the reason behind the mutations that cause it is still largely unknown.

For this reason, treatment options for RTT are limited. Most treatment focuses on symptom relief.

Treatment options that can help a person with RTT include:

  • Medications: Medications can help treat breathing irregularities and motor difficulties. A doctor may also prescribe drugs to help control seizures.
  • Physical therapy and hydrotherapy: This can help a person with their mobility issues and balance.
  • Occupational therapy: Occupational therapy can help a person develop the skills they need to perform tasks such as dressing and feeding.
  • Speech and language therapy: This can help a person learn how to use nonverbal communication and improve their social interaction.
  • Braces: These may be helpful for correcting the effects of scoliosis.
  • Splints: A doctor may use splints to help adjust hand movements.
  • Nutritional help: Supplements can strengthen the bones and assist with scoliosis. Having a specific nutritional program may help the person maintain a moderate weight.

According to one 2018 study, people with RTT can survive into middle and older age. To improve life expectancy, a doctor will give adequate attention to the following areas:

  • orthopedic complications
  • seizure control
  • nutrition

Although focusing on these areas can help a person live into middle and older age, people with RTT do have “a sudden and unexpected death rate of 26%,” according to the study above. This is often due to respiratory infection, cardiac instability, or respiratory failure.

RTT is a rare genetic condition that mostly affects females. The condition causes both physical and mental disabilities.

The main symptoms include slowed development, motor control issues, distinctive hand movements, issues with mobility, intellectual disability, and seizures.

RTT is due to a mutation in a gene on the X chromosome. Treatment focuses on symptom relief, and with the right care and attention, a person with RTT can live into middle and older age.