Rett Syndrome: MECP2 Sequencing

Turnaround Time

3 weeks

CPT Code(s)

81302

Cost

$900

Genes

• Rett syndrome

A neurodevelopmental disorder that affects females, Rett syndrome is associated with cortical atrophy, stereotypical hand movements and severe intellectual disability. With an incidence of 1 in 10,000 - 15,000, it is one of the most common causes of intellectual disability in females. Rett syndrome is characterized by loss of acquired skills after a period of normal development in infancy. Most cases of Rett syndrome are caused by an abnormality (missense mutation, nonsense mutation or deletion) of MECP2. Additionally, a specific phenotype has been identified in males with a MECP2 duplication that is identifiable by MLPA. These males display hypotonia that progresses to spasticity, severe intellectual disability and recurrent pulmonary infections. Females in these families who have the duplication are clinically unaffected and display a near total skewing of X-inactivation. Sequencing of the MECP2 gene and MLPA deletion/duplication analysis can be ordered concurrently, sequentially or separately.

Molecular testing is useful to confirm the diagnosis and to identify the disease causing mutations within a family to allow for carrier testing and prenatal diagnosis.

Sanger Sequencing

Sequencing of the MECP2 gene will detect mutations in approximately 80% of individuals with Rett syndrome. Of those with a normal sequencing result, approximately 15% will have a deletion or duplication identified by MLPA.

The preferred sample type is 3-5 ml of peripheral blood collected in an EDTA (purple top) tube. Extracted DNA, dried blood spots, and saliva are also accepted for this test. Saliva samples must be submitted in an approved saliva kit. Contact the lab to receive a saliva kit or to have one sent to your patient.

The specimen should be kept at room temperature and delivered via overnight shipping. If shipment is delayed by one or two days, the specimen should be refrigerated and shipped at room temperature. Do not freeze the specimen. Samples collected on Friday can be safely designated for Monday delivery.

Prenatal diagnosis is available if the familial mutations are known. Additional fees for cell culture and maternal cell contamination may apply. Maternal cell contamination studies are required for all prenatal molecular tests. Contact the laboratory prior to sending a prenatal specimen.