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HelpTest Code PMPDD PMP22 Gene, Large Deletion/Duplication Analysis, Varies
Reporting Name
PMP22 Gene, Deletion/DuplicationUseful For
Diagnosis of Charcot-Marie-Tooth type 1A or hereditary neuropathy with liability to pressure palsies
Testing Algorithm
For more information see Hereditary Peripheral Neuropathy Diagnostic Algorithm.
Method Name
Dosage Analysis by Polymerase Chain Reaction (PCR)/Multiplex Ligation-Dependent Probe Amplification (MLPA)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
VariesShipping Instructions
Specimen preferred to arrive within 96 hours of collection.
Specimen Required
Patient Preparation: A previous bone marrow transplant from an allogenic donor will interfere with testing. Call 800-533-1710 for instructions for testing patients who have received a bone marrow transplant.
Specimen Type: Whole blood
Container/Tube:
Preferred: Lavender top (EDTA) or yellow top (ACD)
Acceptable: Any anticoagulant
Specimen Volume: 3 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Send specimen in original tube.
Additional Information: To ensure minimum volume and concentration of DNA is met, the preferred volume of blood must be submitted. Testing may be canceled if DNA requirements are inadequate.
Specimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Ambient (preferred) | ||
| Frozen | |||
| Refrigerated | |||
Reject Due To
All specimens will be evaluated by Mayo Clinic Laboratories for test suitability.Special Instructions
Reference Values
Day(s) Performed
Batched 1 time per week
CPT Code Information
81324
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| PMPDD | PMP22 Gene, Deletion/Duplication | 75384-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 113371 | Result Summary | 50397-9 |
| 113374 | Result | 75384-8 |
| 113375 | Interpretation | 69047-9 |
| 113376 | Additional Information | 48767-8 |
| 113377 | Specimen | 31208-2 |
| 113378 | Source | 31208-2 |
| 113379 | Released By | 18771-6 |
Forms
1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available in Special Instructions:
-Informed Consent for Genetic Testing (T576)
-Informed Consent for Genetic Testing-Spanish (T826)
2. Molecular Genetics: Neurology Patient Information in Special Instructions
3. If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen.
Secondary ID
66569Highlights
This test may aid in the diagnosis of Charcot-Marie-Tooth type 1A or hereditary neuropathy with liability to pressure palsies.
Clinical Information
This test is appropriate for individuals with clinical features suggestive of Charcot-Marie-Tooth type 1A (CMT1A) and hereditary neuropathy with liability to pressure palsies (HNPP).
CMT1A is a dominantly inherited disease characterized 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.
Deletions of PMP22 are associated with hereditary neuropathy with liability to pressure palsies (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.
Interpretation
All detected alterations are evaluated according to American College of Medical Genetics and Genomics recommendations.(1) Variants are classified based on known, predicted, or possible pathogenicity and reported with interpretive comments detailing their potential or known significance.
Cautions
In addition to disease-related probes, the multiplex ligation-dependent probe amplification technique utilizes probes localized to other chromosomal regions as internal controls. In certain circumstances, these control probes may detect other diseases or conditions for which this test was not specifically intended. Results of the control probes are not normally reported. However, in cases where clinically relevant information is identified, the ordering physician will be informed of the result and provided with recommendations for any appropriate follow-up testing.
This test may not detect deletions/duplications present in very low levels of mosaicism.
Rare polymorphisms 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.
Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in our interpretation of results may occur if information given is inaccurate or incomplete.
Clinical Reference
1. Richards S, Aziz N, Bale S, et al: Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genet Med 2015 May;17(5):405-424
2. van Paassen BW, van der Kooi AJ, van Spaendonck-Zwarts KY, et al: PMP22 related neuropathies: Charcot-Marie-Tooth disease type 1A and Hereditary Neuropathy with liability to Pressure Palsies. Orphanet J Rare Dis 2014 Mar 19;9:38
3. Li J, Parker B, Martyn C, et al: The PMP22 Gene and Its Related Diseases. Mol Neurobiol 2013 April;47(2):673-698
Method Description
Multiple ligation-dependent probe amplification (MLPA) is utilized to test for the presence of large deletions and duplications within the PMP22 gene.(Unpublished Mayo method)