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MECP2 Sequencing, Full Gene

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MECP2-related Disorders Genetic Testing Patient Flyer
Related Information
  • Clinical Questionnaire for MECP2-related Disorders
Special Instructions A completed screening questionnaire must accompany specimens. Call 800-345-4363 to request forms, or photocopy the form Clinical Questionnaire for MECP2-related Disorders from the Genetics Appendix.
Specimen Whole blood, amniotic fluid, chorionic villus sample (CVS) (Submission of maternal blood is required for fetal testing.) or LabCorp buccal swab kit (The buccal swab collection kit contains instructions for use of a buccal swab.)
Volume 7 mL whole blood, LabCorp buccal swab kit, 10 mL amniotic fluid, or 20 mg CVS
Minimum Volume 3 mL whole blood, two buccal swabs, 5 mL amniotic fluid, or 10 mg CVS
Container Lavender-top (EDTA) tube, yellow-top (ACD) tube, sterile plastic conical tube or two confluent T25 flasks for fetal testing, or LabCorp buccal swab kit
Storage Instructions Maintain specimen at room temperature or refrigerated at 4°C.
Causes for Rejection Frozen specimen; hemolysis; quantity not sufficient for analysis; improper container; wet buccal swab; one buccal swab
Use Detects mutations in the gene for methyl-CpG-binding protein 2 (MECP2), which causes Rett syndrome, a severe neurological disorder leading to regression of developmental behaviors and expressive language skills.
Limitations This test does not detect variants in any other gene, nor does it detect genomic deletions or promoter or deep-intron variants. Molecular-based testing is highly accurate, but as in any laboratory test, rare diagnostic errors may occur.
Methodology DNA sequencing
Additional Information There are some suspected cases in males, but Rett syndrome primarily affects females. It is the second most common cause of mental retardation in females (frequency: 1:15,000 to 1:8,500 births). The risk of development of Rett syndrome seems to be equal among different ethnic groups.

Mutations in the gene for methyl-CpG-binding protein 2 (MECP2) are the most common cause of Rett syndrome. The MECP2 protein is one of the many components involved with the regulation of gene expression. Rett syndrome is considered to be the first syndrome identified directly related to mutations in a gene controlling gene expression.

The MECP2 gene is located on the X chromosome. Currently, the criterion for Rett syndrome diagnosis is completely clinical. A group of standardized clinical benchmarks has been used to identify Rett syndrome and to distinguish relative subsets within the Rett population. The most clinically defined group is referred to as classic Rett. Of these, the majority (80%) have MECP2 gene mutations. Although 12 mutations account for 73% of mutation-positive cases, nearly 300 disease-causing mutations have been identified.
References Amir RE, Van den Veyver IB, Wan M, Tran CQ, Francke U, Zoghbi HY. Rett syndrome is caused by mutations in X-linked MECP2, encoding methyl-CpG binding protein 2. Nat Genet. 1999 Oct; 23(2):185-188. PubMed 10508514

Bienvenu T, Carrie A, de Roux N, et al. MECP2 mutations account for most cases of typical forms of Rett syndrome. Hum Mol Genet. 2000 May 22; 9(9):1377-1384. PubMed 10814719

Buyse IM, Fang P, Hoon KT, Amir RE, Zoghbi HY, Roa BB. Diagnostic testing for Rett syndrome by DHPLC and direct sequencing analysis of the MECP2 gene: Identification of several novel mutations and polymorphisms. Am J Hum Genet. 2000 Dec; 67(6):1428-1436. PubMed 11055898

Christodoulou J, Ho G. MECP2-related disorders. In: Pagon RA, Adam MP, Ardinger HH, et al. GeneReviews. 2001 Oct 03. Available at http://www.genetests.org. Accessed September 2, 2009.PubMed 20301670

Rett Syndrome Diagnostic Criteria Work Group. Diagnostic criteria for Rett syndrome. Ann Neurol. 1988 Apr; 23(4):425-428. PubMed 2454607

Smeets E, Schollen E, Moog U, et al. Rett syndrome in adolescent and adult females: Clinical and molecular genetic findings. Am J Med Genet. 2003 Oct 15; 122A(3):227-233.PubMed 12966523