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Rett syndrome

Rett syndrome is a rare neurodevelopmental disorder primarily affecting females. It is caused by mutations in the MECP2 gene which makes a protein called methyl-CpG-binding protein 2.

Characteristics of Rett syndrome
Rett syndrome is a rare genetic condition that affects the development of the brain and nervous system. Girls with classic Rett syndrome usually have a period of normal development followed by a regression in development (loss of acquired skills) at 6 to 18 months of age. While some developmental skills may be gained back, there is typically a continued loss of previously acquired verbal skills and purposeful hand use. During this period of regression, repetitive hand movements usually begin. Many, though not all, have a normal head size at birth followed by a slowing of head growth after birth. Additional features may include the inability to walk or difficulty walking without assistance, breathing problems (breathing very fast and/or breath holding), teeth grinding (bruxism), seizures, poor growth, curving of the spine (scoliosis/kyphosis), disrupted sleeping patterns, autistic-like behaviors, and panic-like attacks.

Diagnosis/Testing
Rett syndrome can be diagnosed either by meeting certain clinical criteria or by genetic testing for a change or mutation in a gene called MECP2. This gene makes the methyl-CpG-binding protein 2. This protein is thought to help control the activity of certain genes, and is also thought to be important for the development of brain cells. Mutations in the MECP2 gene may interfere with the protein’s normal function and the ability to interact with certain genes that are important for normal development and function.

Management/Surveillance
The management of Rett syndrome is based on the symptoms of the individual. Typically, physical, occupational, and speech therapies are required to improve developmental skills following the initial regression phase. Anti-seizure medications, nutrition supplementation, and other treatments are used as needed.
Individuals with Rett syndrome are also at an increased risk for certain changes in heart function that can cause the heart to beat irregularly. Periodic EKGs (tests that monitor the electrical activity of the heart) is often needed to watch for these changes.

Mode of inheritance
Rett syndrome is inherited in an X-linked dominant pattern. This means only one copy of the MECP2 gene whether in a female with two X chromosomes or in a male with one X chromosome must have a change or mutation for an individual to be affected with Rett syndrome. It is thought that in males, Rett syndrome is fatal before birth because a second normal X chromosome is needed for survival to birth. However, some males with Rett syndrome (or variants of Rett syndrome) have been reported. In most individuals, the mutation in the MECP2 gene occurs brand new (de novo). However in about 1% of cases, the mutation is inherited from the mother.

Risk to family members
The risk to family members depends on whether or not the individual with Rett syndrome inherited the mutation or if the mutation occurred de novo. Since the vast majority of individuals with Rett syndrome have a de novo mutation, the risk of other siblings being affected is very low.

Special considerations
None

Resources
International Rett Syndrome Foundation
Cure Rett
Genetics Home Reference: Rett syndrome
Medical Home Portal: Rett Syndrome

References
Christodoulou J, Ho G. (Updated 28 June 2012). MECP2-Related Disorders. In: GeneReviews at GeneTests Medical Genetics Information Resource (database online). Copyright, University of Washington, Seattle. 1997-2013. Available at http://www.ncbi.nlm.nih.gov/books/NBK1497/. Accessed [09/06/2013].
Matijevic, T. et al. (2009)."Rett Syndrome: From the Gene to the Disease." European Neurology 61(1): 3-10.
Neul, JL. et al. (2010)."Rett syndrome: revised diagnostic criteria and nomenclature." Annals of Neurology 68(6): 944-950.
Percy, AK. et al. (2010)."Rett Syndrome Diagnostic Criteria: Lessons from the Natural History Study." Annals of Neurology 68(6): 951-955.
Samaco, RC. et al. (2011)."Complexities of Rett Syndrome and MeCP2." Journal of Neuroscience 31(22): 7951-7959.
Smeets, EE. et al. (2012)."Rett Syndrome." Molecular Syndromology 2(3-5): 113-127.

Created:09/2013

Updated:mm/yyyy

Created by:Lauren M. Baggett, MS, CGC

Edited by:Seema Jamal, MSc, LCGC



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