Ordering Recommendation

Acceptable initial test for clinical diagnosis of Rett syndrome or MECP2-related disorder. Consultation with a genetic counselor is recommended to plan the optimal MECP2 genetic testing sequence. ARUP's genetic counselors are available at 800-242-2787 x2141

Mnemonic
RETT FGS
Methodology

Polymerase Chain Reaction/Sequencing

Performed

Varies

Reported

10-14 days

New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
Collect

Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).

Specimen Preparation

Transport 3 mL whole blood. (Min: 1 mL)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions
Remarks
Stability

Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable

Reference Interval

By report

Interpretive Data

Background Information:
Characteristics:
Classic Rett Syndrome is a progressive neurodevelopmental disorder characterized by normal development until 6-18 months of age, followed by rapid developmental regression, deceleration of head growth, loss of speech and acquired motor skills, and seizures; purposeful use of hands is replaced by repetitive stereotyped hand movements. MECP2-related disorders include Rett-like Syndrome, severe congenital encephalopathy, or mild to severe mental retardation.
Incidence: 1in 10,000
Inheritance: X-linked dominant; most cases are sporadic.
Cause: Methyl-CpG-Binding Protein 2 (MECP2) gene mutations.
Clinical Sensitivity: 80%
Methodology: Bidirectional sequencing of the MECP2 coding regions (exons 1-4) and intron-exon boundaries.
Analytical Sensitivity: 99%
Analytical Specificity: 99%
Limitations: Deep intronic mutations and large deletions/duplications will not be identified. Diagnostic errors can occur due to rare sequence variations.

Compliance Category

Laboratory Developed Test (LDT)

Note
Hotline History
N/A
CPT Codes

81302

Components
Component Test Code* Component Chart Name LOINC
0051379 Rett Syndrome, Full Gene Sequencing
2001375 RETT FGS Specimen
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • MECP2 sequencing assay
Rett Syndrome (MECP2), Full Gene Sequencing