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Rett Syndrome - Description
Description
Rett syndrome (RS) first appears in infancy or, more typically, early childhood and has no racial or ethnic predilection. It is a clinical neurodevelopmental syndrome seen primarily in females. Features include:- normal development until approximately 1 to 1.5 years, followed by developmental regression
- loss of purposeful hand movements and onset of characteristic hand wringing
- growth retardation, particularly in head circumference, which is normal at birth but becomes microcephalic
- breathing difficulties, including hyperventilation, apnea, and air swallowing
- seizures in approximately 90% of individuals
- autistic behaviors, including mouthing, hand movements, sighing, and decreased verbalization
- teeth grinding, difficulty chewing, swallowing problems
- severe to profound mental retardation (see the Intellectual disability/mental retardation module)
- truncal ataxia and ataxic gait
- dystonia and spasticity
- in older girls, scoliosis, osteoporosis, and hand and foot deformities
The American College of Medical Genetics recommends that testing for the MECP2 gene mutation should be considered in females with unexplained moderate to severe mental retardation, even without the other clinical features. See [Moeschler: 2006].
Genetics
Most cases of RS are due to mutations in the MECP2 gene on the X chromosome, although up to 20% of girls with the clinical picture of RS will have negative MECP2 testing. However, in China up to 96% of girls with RS features have MECP2 mutations. [Wong: 2007] It has also become clear that MECP2-related disorders comprise many more clinical syndromes than RS, including atypical RS, a severe newborn encephalopathy in males, and possibly X-linked mental retardation without other clinical features of RS. Thus, RS is a MECP2-related disorder but not all MECP2-related disorders are RS. However, RS and MECP2-related disorders are commonly used as synonymous terms. See Genetics of Rett syndrome for more detailed information.Prognosis
Although developmental regression occurs in RS, it is not a degenerative disorder and survival into adulthood is usual. There are however, more sudden unexplained deaths in the RS population than in the general population. The incidence of sudden unexplained deaths is higher in those girls with decreased mobility, difficult to control seizures, and swallowing problems. Sudden unexplained death may be related to heart rhythm abnormalities (including prolonged QT intervals), seizures, or choking. Overall survival in Australia was 77.8% at 25 years when assessed in 2004. [Laurvick: 2006]Prevalence
Overall prevalence in Australia in 2004 was 1 in about 15,000 females, and the prevalence in girls age 5-18 years was 1 in 11,364. ([Laurvick: 2006]) The prevalence in China is 1 in approx 17,500 females under 35 years. ([Wong: 2007])Impact
MECP2-related disorders, including RS, are one of the leading causes for global developmental delay in females.Helpful Articles
PubMed search on Rett syndrome: review articles over the last 5 years
Laurvick CL, de Klerk N, Bower C, Christodoulou J, Ravine D, Ellaway C, Williamson S, Leonard H.
Rett syndrome in Australia: a review of the epidemiology.
J Pediatr.
2006;148(3):347-52.
PubMed abstract
Rett Syndrome Module Authors
| Author: | Lynne M Kerr MD, PhD, 1/2009 |
| Reviewing Author: | Karin Dent MS, CGC, 6/2008 |
| Content Last Updated: | 1/2009 |
The authors listed above are responsible for the overall Rett Syndrome Module. Authors contributing to individual pages in the module are listed on those pages.
Page Bibliography
Laurvick CL, de Klerk N, Bower C, Christodoulou J, Ravine D, Ellaway C, Williamson S, Leonard H.
Rett syndrome in Australia: a review of the epidemiology.
J Pediatr.
2006;148(3):347-52.
PubMed abstract
Moeschler JB, Shevell M.
Clinical genetic evaluation of the child with mental retardation or developmental delays.
Pediatrics.
2006;117(6):2304-16.
PubMed abstract / Full Text
This report describes the "optimal clinical genetics evaluation" for children with developmental delay or mental retardation
for medical home providers.
Wong VC, Li SY.
Rett syndrome: prevalence among Chinese and a comparison of MECP2 mutations of classic Rett syndrome with other neurodevelopmental
disorders.
J Child Neurol.
2007;22(12):1397-400.
PubMed abstract