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
Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
Transport 3 mL whole blood. (Min: 1 mL)
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
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.
Laboratory Developed Test (LDT)
|Component Test Code*||Component Chart Name||LOINC|
|0051379||Rett Syndrome, Full Gene Sequencing|
|2001375||RETT FGS Specimen|
- MECP2 sequencing assay