What is Rett Syndrome (Pervasive Developmental Disorder)

Rett syndrome (RS) is a neurological disorder which also affects many other systems in the body. In 1965 Andreas Rett, an Australian physician identified a syndrome in 22 girls who, after 6 months of apparently normal development, deteriorated in a devastating fashion.

Statistics on Rett Syndrome (Pervasive Developmental Disorder)

The incidence of RS varies widely in different studies from 1 in 10 000 to 1 in 45 000, on average it is 1 in 23 000. It affects females almost exclusively.

Risk Factors for Rett Syndrome (Pervasive Developmental Disorder)

Most cases (99.5%) are due to spontaneous mutations, rather than being inherited. However, the incidence of familial cases is higher than would be expected by chance, so there may be involvement of a genetic factor.

Progression of Rett Syndrome (Pervasive Developmental Disorder)

Children with this condition have problems with physical and social development. They generally suffer the loss of many motor, or movement, skills – such as walking and use of their hands – and develop poor coordination. In addition, there is loss of language skills previously acquired.
RS generally becomes evident when the patient 2-4 years of age; however, the underlying developmental problems may starts in infants as young as 6 months. The patient goes through a period where development remains static followed by a period of developmental regression. Disease progression stabilizes in many patients once they reach adolescence and although they may regain some function they never fully recover. Death in RS patients can occur suddenly and is often secondary to pneumonia.
Many patients with RS also have scoliosis. With the progression of disease, muscle tone seems to change from hypotonia to spasticity to rigidity and subsequent wasting, resulting in many patients being wheelchair bound after 10 years.

How is Rett Syndrome (Pervasive Developmental Disorder) Diagnosed?


  • Genetic testing looking for mutations in the MECP2 gene.
  • Tests that will exclude other possible causes of the patients symptoms and signs include; serum lactate, ammonia, pyruvate, and amino acids, urine organic acids and chromosomal analysis.
  • MRI can also exclude other diagnosis. Findings in RS include decreased size of the cerebral cortex size and cerebellar atrophy.
  • ECG abnormalities may be present.
  • Barium swallow or overnight pH probe to diagnose GOR.
  • EEG for assessing seizures.
  • Psychometric testing which generally indicates severe intellectual impairment.


Prognosis of Rett Syndrome (Pervasive Developmental Disorder)

Patients with RS generally survive into their fifth or sixth decade of life and there have been reports of women surviving into their seventies.
Risk factors that decrease life expectancy include epilepsy, loss of mobility, and swallowing difficulties.
It is difficult to predict the neurodevelopmental outcomes in patients with RS. Some patients retain some functional ability and 60% of patients with RS will continue to walk, however others will have severe disabilities.
With appropriate medical care, physiotherapy, occupational therapy and good nutrition life expectancy is dramatically increased.

How is Rett Syndrome (Pervasive Developmental Disorder) Treated?

There is currently no cure for RS so treatment is supportive. A plan of therapy must be developed with the child’s specific needs in mind. This aims to address the child’s needs at home and at school. This requires significant cooperation between the parents, healthcare providers, teachers and others who may be needed to provide services, such as counselors, social workers and occupational, physical or speech therapists. Such a plan aims to improve socialising and communication skills, as well as improving ability to function.
Some of the different interventions used might include:

  • Physiotherapy to prevent contractures of the hands.
  • Behavioural therapy to help improve self-harming behaviours.
  • Epilepsy: antiepileptic medications may be used to treat seizure activity.
  • Gastroesophageal reflux treatment; Metoclopramide, thickened feeding solutions, and semi upright positioning at bedtime may all help to reduce reflux. If these fail surgery may be necessary.
  • Scoliosis: Bracing may be needed and surgery is an option in patients with pain or loss of function.
  • Constipation: High fibre diet, stool softeners and exercise should help.


Rett Syndrome (Pervasive Developmental Disorder) References

[1] eMedicine
[2] Medline Plus
[3] Amir RE, Van den Veyver IB, Wan M, et al: Rett syndrome is caused by mutations in X-linked MECP2, encoding methyl- CpG-binding protein 2. Nat Genet 1999 Oct; 23(2): 185-8
[4] Hagberg B, Berg M, Steffenburg U: Rett Syndrome – an odd handicap affecting girls. A current 25-year follow-up in western Sweden. Lakartidningen 1999; 96(49): 5488-90
[5] Kaplan and Sadock’s Synopsis of Psychiatry, 9th ed.