PMP22 Gene, Large Deletion/Duplication Analysis, Varies
Use
This test is appropriate as a first-tier test for individuals with clinical features suggestive of Charcot-Marie-Tooth type 1A (CMT1A) and/or hereditary neuropathy with liability to pressure palsies (HNPP). Charcot-Marie-Tooth type 1A is a dominantly inherited disease characterized by progressive distal muscle weakness and atrophy, sensory loss, and slow nerve conduction velocity starting early in life. Duplications of the PMP22 gene are associated with CMT1A and are thought to account for 45%-50% of all CMT and up to 80% of demyelinating CMT. Deletions of PMP22 are associated with HNPP, a dominantly inherited disease resulting in peripheral neuronal demyelination. HNPP is characterized clinically by recurrent focal motor and sensory neuropathy in a single nerve that can manifest as numbness, muscular weakness, and atrophy. Deletions of PMP22 are thought to account for up 80% of HNPP.
Special Instructions
Informed consent is required for New York clients. Document on the request form or electronic order that a copy is on file. Specimens are preferred to be received within 4 days of collection. Extraction will be attempted for specimens received after 4 days, and DNA yield will be evaluated to determine if testing may proceed.
Limitations
This test assesses for large deletions and duplications only. The MLPA technique utilizes probes localized to other chromosomal regions as internal controls, which may detect other diseases. In cases where clinically relevant information is identified, the ordering physician will be informed. The test may not detect deletions/duplications present in very low levels of mosaicism. Rare alterations exist that could lead to false-negative or false-positive results. If results obtained do not match the clinical findings, additional testing should be considered.
New York Approved
Methodology
PCR-based (MLPA)
Biomarkers
LOINC Codes
- 75384-8
- 50397-9
- 75384-8
- 69047-9
- 48767-8
- 31208-2
- 18771-6
Result Turnaround Time
14-21 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
3 mL
Minimum Volume
Not provided
Container
Lavender top (EDTA) or yellow top (ACD)
Collection Instructions
Invert several times to mix blood. Send specimen in original tube. Do not aliquot. Whole blood collected postnatal from an umbilical cord is also acceptable.
Patient Preparation
A previous hematopoietic stem cell transplant from an allogenic donor will interfere with testing.
Causes for Rejection
Specimens will be evaluated for test suitability.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 4 days |
| Refrigerated | 4 days |
| Frozen | 4 days |