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Rett syndrome
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Rett syndrome

Rett syndrome is a rare brain disorder that primarily affects girls, characterized by a period of normal development followed by severe regression in language, communication, learning, and coordination, often accompanied by distinctive hand movements and other neurological symptoms.

Overview

Rett syndrome is a brain disorder that occurs almost exclusively in girls. The most common form of the condition is known as classic Rett syndrome. After birth, girls with classic Rett syndrome have 6 to 18 months of apparently normal development before developing severe problems with language and communication, learning, coordination, and other brain functions. Early in childhood, affected girls lose purposeful use of their hands and begin making repeated hand wringing, washing, or clapping motions. They tend to grow more slowly than other children and about three-quarters have a small head size (microcephaly). Other signs and symptoms that can develop include breathing abnormalities, spitting or drooling, unusual eye movements such as intense staring or excessive blinking, cold hands and feet, irritability, sleep disturbances, seizures, and an abnormal side-to-side curvature of the spine (scoliosis).

Researchers have described several variant or atypical forms of Rett syndrome, which can be milder or more severe than the classic form.

Rett syndrome is part of a spectrum of disorders with the same genetic cause. Other disorders on the spectrum include PPM-X syndrome, MECP2 duplication syndrome, and MECP2-related severe neonatal encephalopathy. These other conditions can affect males.

Frequency

This condition affects an estimated 1 in 9,000 to 10,000 females.

Causes

Mutations in a gene called MECP2 underlie almost all cases of classic Rett syndrome and some variant forms of the condition. This gene provides instructions for making a protein (MeCP2) that is critical for normal brain function. Although the exact function of the MeCP2 protein is unclear, it is likely involved in maintaining connections (synapses) between nerve cells (neurons). It may also be necessary for the normal function of other types of brain cells.

The MeCP2 protein is thought to help regulate the activity of genes in the brain. This protein may also control the production of different versions of certain proteins in brain cells. Mutations in the MECP2 gene alter the MeCP2 protein or result in the production of less protein, which appears to disrupt the normal function of neurons and other cells in the brain. Specifically, studies suggest that changes in the MeCP2 protein may reduce the activity of certain neurons and impair their ability to communicate with one another. It is unclear how these changes lead to the specific features of Rett syndrome.

Several conditions with signs and symptoms overlapping those of Rett syndrome have been found to result from mutations in other genes. These conditions, including FOXG1 syndrome and CDKL5 deficiency disorder, were previously thought to be variant forms of Rett syndrome. However, doctors and researchers have identified some important differences between the conditions, so they are now usually considered to be separate disorders.

Associated Gene

  • MECP2

Inheritance

In more than 99 percent of people with Rett syndrome, there is no history of the disorder in their family. Many of these cases result from new mutations in the MECP2 gene.

A few families with more than one affected family member have been described. These cases helped researchers determine that classic Rett syndrome and variants caused by MECP2 gene mutations have an X-linked dominant pattern of inheritance. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes. The inheritance is dominant if one copy of the altered gene in each cell is sufficient to cause the condition.

Males with mutations in the MECP2 gene often die in infancy. However, a small number of males with a genetic change involving MECP2 have developed signs and symptoms similar to those of Rett syndrome, including intellectual disability, seizures, and movement problems. In males, this condition is described as MECP2-related severe neonatal encephalopathy. The signs and symptoms in some males with an MECP2 gene mutation are on the milder end of the spectrum.

Other Names for This Condition

  • Autism-dementia-ataxia-loss of purposeful hand use syndrome
  • Rett disorder
  • Rett's disorder
  • Rett's syndrome
  • RTT

Frequently Asked Questions

First‑line seizure control usually involves broad‑spectrum antiepileptic drugs such as levetiracetam or valproic acid, titrated to EEG findings; for breathing dysregulation, nighttime oxygen monitoring, occasional use of low‑dose baclofen or serotonergic agents, and positioning strategies (elevated head of bed) can reduce apneas and hyperventilation episodes.
Most individuals survive into adulthood, with life expectancy often extending beyond 40 years; however, progressive scoliosis, severe motor impairment, and autonomic dysfunction may increase care needs. Early involvement of multidisciplinary teams (neurology, pulmonology, orthopedics, occupational therapy, and social services) and advance‑care planning are essential for housing, equipment, and caregiver support.
The most concerning early clues are loss of purposeful hand use, the appearance of repetitive hand‑wringing or clapping motions, a sudden slowdown in language acquisition, and regression in social engagement; these often emerge between 6‑18 months after a period of typical milestones.
Diagnosis combines clinical criteria (regression of skills, hand stereotypies, gait abnormalities, etc.) with molecular testing; sequencing of the MECP2 gene on a blood sample detects >95 % of classic cases and is the standard confirmatory test.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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