Atypical Rett syndrome is a type of the condition that occurs when a person has some of the symptoms of Rett syndrome, but does not meet all of the diagnostic criteria.

Rett syndrome (RTT) is a rare genetic condition causing mental and physical disabilities. Both RTT and atypical RTT almost exclusively occur in females. In rare cases, they can also affect males.

RTT is rare and affects an estimated 1 in 10,000 females by the age of 12 years in the United States. Atypical RTT is a genetic condition, and symptoms can start to appear when the infant is in the newborn phase.

Read on to learn more about what atypical RTT is and how it differs from RTT.

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Atypical RTT is a genetic neurodevelopmental disorder. It causes a child to develop both physical and mental disabilities.

A medical professional will diagnose a child with atypical RTT if they have some of the symptoms of RTT but do not meet all of the diagnostic criteria for RTT.

RTT and atypical RTT are very similar, but they do have distinct differences.

A child may receive a diagnosis of RTT if they experience a period of regression followed by recovery or stabilization and display all 4 of the main criteria for RTT.

The 4 main criteria for RTT are:

  1. partial or complete loss of acquired purposeful hand skills
  2. partial or complete loss of acquired spoken language
  3. gait abnormalities
  4. stereotypic hand movements, such as:
    • hand wringing or squeezing
    • clapping or tapping
    • mouthing and washing or rubbing actions

A child may receive a diagnosis of atypical RTT if they:

  • experience a period of regression followed by recovery or stabilization
  • display at least 2 (but not all 4) of the main criteria for RTT
  • display 5 of the 11 supportive criteria for RTT

The 11 supportive criteria for RTT are:

  1. breathing problems when awake
  2. jaw clenching (bruxism) when awake
  3. problems sleeping
  4. abnormal muscle tone
  5. peripheral vasomotor disturbances
  6. scoliosis or kyphosis
  7. slowed growth
  8. small and cold hands and feet
  9. inappropriate spells of laughing or screaming
  10. a diminished response to pain
  11. intense eye communication, such as eye pointing

If a person has typical RTT, a medical professional does not require the supportive criteria to make a diagnosis. To diagnose both typical and atypical RTT, a doctor must ensure the child has not experienced a brain injury due to trauma or a severe infection.

A child may begin to display symptoms of atypical RTT when they are a newborn. However, the age at which symptoms appear can differ from person to person.

The most common symptoms of atypical RTT include:

  • breathing difficulties
  • abnormal movements characterized by changes in coordination and speed of voluntary movements
  • restlessness and agitation
  • problems with social interactions and communication
  • developmental regression
  • problems eating
  • functional motor issues
  • problems walking
  • intellectual disability
  • involuntary movements
  • poor eye contact
  • seizures
  • problems sleeping
  • habitual clasping and squeezing of the hands

A child with atypical RTT may have symptoms that are milder or more severe than those seen in RTT.

Most causes of RTT occur due to an alteration in the methyl CpG binding protein 2 (MECP2) gene. Some cases of atypical RTT may result from variations in the cyclin-dependent kinase-like 5 (CDKL5) gene.

Despite being a genetic condition, less than 1% of recorded cases occur due to one generation passing the gene variation to the next. This means most cases of RTT are spontaneous, with the alteration occurring randomly.

A doctor will diagnose RTT by observing the infant’s signs and symptoms. They will then conduct ongoing evaluations of the infant’s physical and neurological status.

To confirm their diagnosis, they may carry out a specific genetic test. This test can help detect the specific variations that cause both typical and atypical RTT. To carry out the test, a medical professional will first send a blood sample to a lab for analysis.

Currently, there is no cure for RTT. This means that most treatments aim to reduce symptoms.

Treatments for RTT include:

  • Speech and language therapy: An infant can undergo speech and language therapy to help them develop nonverbal communication methods. This may help them improve the way they interact with others.
  • Medications: An infant may take certain medications to help improve any issues they have with breathing and mobility. There are also anti-epileptic medications that can help control seizures resulting from RTT.
  • Physical therapy: Physical therapy can help improve a child’s mobility. A physical therapist may also aim to improve their sitting posture to reduce their chances of developing scoliosis.
  • Dietary changes: An infant with RTT may benefit from a high-calorie, low-carbohydrate diet. This can help them achieve and maintain a sufficient weight and can help control seizures.
  • Occupational therapy: This can help develop skills required to help the child with their daily activities. This may include skills to help them dress and feed themselves.
  • Braces: These can help correct the effects of scoliosis. Lower leg braces can also help the child walk independently.
  • Splints: Splints can help adjust specific hand movements.

RTT is a rare genetic condition that causes mental and physical disabilities. A person has atypical RTT if they have some of the symptoms of RTT but do not meet all of the diagnostic criteria for RTT.

Symptoms of atypical RTT include problems breathing, problems eating, problems walking, developmental regression, intellectual disability, and seizures.

There is currently no cure for typical or atypical RTT. This means that treatment for both conditions involves reducing symptoms. Treatment involves physical therapy, occupational therapy, speech and language therapy, and certain medications.