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MECP2 Testing

The diagnosis of RTT is based upon a detailed clinical evaluation and patient history. A blood test to screen for mutations in the MECP2 gene has been available since late 1999. Although testing positive for a mutation confirms the diagnosis it is not required. Other tests may be conducted to eliminate possible neurodegenerative, neurometabolic or other disorders that may have similar symptoms.

For laboratories that perform MECP2 analysis please
click here.

If a sample has tested negative for MECP2 mutations there is now further testing that is available.

Picture the MECP2 gene as a book with 4 chapters. Mutations may include having a missing page(s), an extra page(s) or pages in the wrong order. In some cases an entire chapter or two chapters may be missing. The correct term for the chapters is exons.

Until March of 2004 it was thought that only mutations in exons 2-3-4 could lead to Rett Syndrome. In March of 2004 the Bird lab and the Minassian lab announced the discovery of a new form of MeCP2. The new protein, which is 3% longer then the original form, is 10 times more abundant in the brain. This longer section is exon 1. Although mutations in exon 1 are rare testing is now available.

Furthermore testing aimed at finding large deletions (entire chapter(s)) has recently become available.

If a child has tested negative for MECP2 mutations in the past please consider these additional tests.

Large Deletion Testing and
Exon 1 Testing
As of September 1, 2004 the Medical Genetics Laboratories at Baylor is offering MECP2 mutation screening for exon 1 and large deletions testing using a technique called Southern analysis. Information regarding the test is available on the Baylor website.

Large Deletion Testing
Greenwood Genetic Center is offering large deletion testing with a technique called Multiplex Ligation-dependent Probe Amplification (MLPA). They do not, at this time, perform exon 1 testing. To send a sample please download the one-page test requisition form available on this website. Please check off the box for Rett Syndrome but make sure you specifically request MLPA testing by writing in MLPA next to the words Rett Syndrome.

Draw 5 ml of blood sample in a purple top test tube. Make sure the test tube is labeled with individual's name and date of birth.
If possible include a report confirming a clinical diagnosis for your child.

Send via OVERNIGHT delivery to: (DO NOT send on a Friday)

friez@ggc.org

STK9 Gene Testing
John Christodoulou of the Children's Hospital at Westmead, Sydney, Australia recently identified mutations in a gene called STK9, that may be associated with a Rett-like presentation. Dr. Christodoulou is interested in testing samples of patients with Rett symptoms but no MECP2 mutations. To send a sample please download these forms and follow the instructions.

If you have questions regarding MECP2 mutation testing please contact Monica Coenraads, Director of Research for RSRF, at Monica Coenraads.

Worldwide efforts are ongoing to make the screening of the MECP2 gene as comprehensive as possible. We suspect the majority of the 10-15% who are testing negative do, in fact, have a mutation in this gene which will be found as the testing becomes more refined. To stay up to date regarding new testing please subscribe to the RSRFNewsAlert.