Rett syndrome is an X-linked neurodevelopmental disorder caused by mutations in the MECP2 gene which encodes the Methyl CpG Binding Protein 2 transcriptional repressor. Rett syndrome affects ~1 in 10,000 females with symptoms including loss of speech and purposeful hand use, microcephaly, seizures, ataxia, and stereotypic hand movements. MECP2 mutations manifest a broader spectrum of clinical phenotypes in female and rare male patients, with features overlapping with other mental retardation disorders. Mutations in the MECP2 coding region can be detected by sequence analysis in up to ~85% of Rett cases. Our laboratory offers DNA sequencing analysis of MECP2 exons 1 through 4.

Previously, testing laboratories had performed sequence analysis of the MECP2 coding region which was thought to consist of exons 2 through 4. Recently, rare mutations in MECP2 exon 1 have been reported in a few Rett patients. For patients who had previously tested negative by sequence analysis of exons 2 through 4, targeted sequencing analysis of MECP2 exon 1 can be requested through our laboratory. More significantly, testing may be considered for MECP2 gene deletions which have been identified in approximately 10% of Rett patients. (See MECP2 Deletion Analysis which is offered as a separate test).

Reasons for Referral:

• Diagnostic testing.
• Prenatal testing for known familial mutation.

Testing Methodology:

DNA Sequencing of MECP2 exons 1 through 4 in both directions using a 96-capillary sequencer.

Sensitivity:

Sequencing has an analytical sensitivity of ~99% for point mutations. Up to ~85% of classic Rett patients have MECP2 gene mutations that can be identified by sequencing.

Specimen Requirements:

Blood: EDTA (purple-top) tubes: Adults: 14 cc; Child: 6 cc; Infant: 6 cc
Please contact the laboratory for specific requirements for prenatal testing.

Turnaround Time:

3 weeks

CPT Codes and Prices:

Index: 83904x7, 83912, 83909x14, 83898x10, 83894, 83891
Known Familial Mutation: 83904x4, 83912, 83909x4, 83898x2, 83894, 83891

References:

1. Amir R, et al. (1999) Nat. Genet. 23: 185-188.
2. Amir RE, Zoghbi HY. (2000) Am. J. Med. Genet. 97: 147-152.
3. Mnatzakanian GN, et al. (2004) Nat. Genet. 36: 339-342.
4. Laccone F, et al. (2004) Hum. Mutat. 23: 234-244.

Shipping Information

Forms:

 >> Gene Sequencing Requisition
 >> Prenatal Requisition

Test Codes:

Index: 6068
Known Familial Mutation: 6108
Prenatal (Known Familial Mutation Only): 6110

Medical Genetics Laboratories
Baylor College of Medicine · Houston, TX 77030
Phone: 1-800-411-GENE · Fax: 713-798-6584
E-mail: