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Autism Spectrum Disorders Health Center

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Rett Syndrome

It is possible that the main title of the report Rett Syndrome is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.


  • RTT
  • classic Rett syndrome
  • variant (atypical) Rett syndrome

Disorder Subdivisions

  • None

General Discussion

Rett syndrome is a progressive neurodevelopmental disorder that almost exclusively affects females. Only in rare cases are males affected. Infants with Rett syndrome generally develop normally for about 7 to 18 months after birth. At this point, they lose previously acquired skills (developmental regression) such as purposeful hand movements and the ability to communicate. Additional abnormalities occur including impaired control of voluntary movements (ataxia) and the development of distinctive, uncontrolled hand movements such as hand clapping or rubbing. Some children also have slowing of head growth (acquired microcephaly), Affected children often develop autistic-like behaviors, breathing irregularities, feeding and swallowing difficulties, growth retardation, and seizures. Most Rett syndrome cases are caused by identifiable mutations of the MECP2 gene on the X chromosome and can present with a wide range of disability ranging from mild to severe. The course and severity of Rett syndrome is determined by the location, type and severity of the MECP2 mutation and the process of random X-inactivation (see Causes section below). Therefore, two girls of the same age with the same mutation can appear significantly different.

Rett syndrome was first described in the medical literature by an Austrian physician named Andreas Rett in 1960s. Many researchers now consider Rett syndrome as part of a spectrum of disease relating to mutations of the MECP2 gene. This spectrum, sometimes referred to as MECP2-related disorders, includes classic Rett syndrome, variant Rett syndrome, MECP2-related severe neonatal encephalopathy, and PPM-X syndrome. Another disorder, MECP2 duplication syndrome, has recently been described in the medical literature. This disorder is caused by duplicated material involving the MECP2 gene on the X chromosome.


WE MOVE (Worldwide Education and Awareness for Movement Disorders)
5731 Mosholu Avenue
Bronx, NY 10471
Tel: (347)843-6132
Fax: (718)601-5112

March of Dimes Birth Defects Foundation
1275 Mamaroneck Avenue
White Plains, NY 10605
Tel: (914)997-4488
Fax: (914)997-4763
Tel: (888)663-4637

The Arc
1825 K Street NW, Suite 1200
Washington, DC 20006
Tel: (202)534-3700
Fax: (202)534-3731
Tel: (800)433-5255
TDD: (817)277-0553

International Rett Syndrome Foundation
4600 Devitt Dr.
Cincinnati, OH 45246
Tel: (800)818-7388

NIH/National Institute of Neurological Disorders and Stroke
P.O. Box 5801
Bethesda, MD 20824
Tel: (301)496-5751
Fax: (301)402-2186
Tel: (800)352-9424
TDD: (301)468-5981

New Horizons Un-Limited, Inc.
811 East Wisconsin Ave
P.O. Box 510034
Milwaukee, WI 53203
Tel: (414)299-0124
Fax: (414)347-1977

Genetic and Rare Diseases (GARD) Information Center
PO Box 8126
Gaithersburg, MD 20898-8126
Tel: (301)251-4925
Fax: (301)251-4911
Tel: (888)205-2311
TDD: (888)205-3223

Madisons Foundation
PO Box 241956
Los Angeles, CA 90024
Tel: (310)264-0826
Fax: (310)264-4766

Child Neurology Foundation
201 Chicago Ave, #200
Minneapolis, MN 55415
Tel: (952)641-6100
Fax: (952)881-6276
Tel: (877)263-5430

Medical Home Portal
Dept. of Pediatrics
University of Utah
P.O. Box 581289
Salt Lake City, UT 84158
Tel: (801)587-9978
Fax: (801)581-3899

For a Complete Report:

This is an abstract of a report from the National Organization for Rare Disorders (NORD). A copy of the complete report can be downloaded free from the NORD website for registered users. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational therapies (if available), and references from medical literature. For a full-text version of this topic, go to and click on Rare Disease Database under "Rare Disease Information".

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians.

It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report

This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

For additional information and assistance about rare disorders, please contact the National Organization for Rare Disorders at P.O. Box 1968, Danbury, CT 06813-1968; phone (203) 744-0100; web site or email

Last Updated: 10/11/2012
Copyright 1986, 1987, 1994, 1995, 1998, 1999, 2000, 2001, 2002, 2004, 2007, 2012 National Organization for Rare Disorders, Inc.

WebMD Medical Reference from the National Organization for Rare Disorders

Last Updated: May 28, 2015
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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