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


Polymerase Chain Reaction/Sequencing




10-14 days

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

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

Specimen Preparation

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

Storage/Transport Temperature


Unacceptable Conditions

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

Reference Interval

By report

Interpretive Data

Background Information:
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.

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Compliance Category

Laboratory Developed Test (LDT)

Hotline History
CPT Codes


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.
  • MECP2 sequencing assay
Rett Syndrome (MECP2), Full Gene Sequencing