This is a second tier diagnostic test for Rett syndrome. 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).
- 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
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 the 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: 1 in 10,000.
Inheritance: X-linked dominant; most cases are sporadic.
Cause: Methyl-CpG-Binding Protein 2 (MECP2) gene mutations.
Clinical Sensitivity: Up to 15 percent.
Methodology:Multiplex Ligation-dependent Probe Amplification (MLPA) to detect large deletions/duplications in the MECP2 coding regions (exons 1-4).
Analytical Sensitivity: 90 percent.
Analytical Specificity: 98 percent.
Limitations: Breakpoints of large deletions/duplications cannot be determined; deep intronic mutations, single base pair substitutions and small deletions/duplications will not be detected; analytical sensitivity may be compromised by rare primer site mutations. Diagnostic errors can occur due to rare sequence variations.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.
|Component Test Code*||Component Chart Name||LOINC|
|0051617||Rett Syndrome, Deletion and Duplication|
- MECP2 deletion/duplication assay