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HelpTest Code PMPDD PMP22 Gene, Large Deletion/Duplication Analysis, Varies
Shipping Instructions
Specimen Required
Patient Preparation: A previous hematopoietic stem cell transplant from an allogenic donor will interfere with testing. For instructions for testing patients who have received a hematopoietic stem cell transplant, call 800-533-1710.
Submit only 1 of the following specimens:
Specimen Type: Whole blood
Container/Tube:
Preferred: Lavender top (EDTA) or yellow top (ACD)
Acceptable: None
Specimen Volume: 3 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Send whole blood specimen in original tube. Do not aliquot.
Specimen Stability Information: Ambient (preferred) 4 days/Refrigerated 4 days/Frozen 4 days
Additional Information:
1. 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.
2. To ensure minimum volume and concentration of DNA is met, the requested volume must be submitted. Testing may be canceled if DNA requirements are inadequate.
Specimen Type: Cord blood
Container/Tube:
Preferred: Lavender top (EDTA) or yellow top (ACD)
Acceptable: None
Specimen Volume: 3 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Send specimen in original tube. Do not aliquot.
Specimen Stability Information: Ambient (preferred) 4 days/Refrigerated 4 days/Frozen 4 days
Additional Information:
1. 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.
2. 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.
3. While a properly collected cord blood sample may not be at risk for maternal cell contamination, unanticipated complications may occur during collection.
Therefore, maternal cell contamination studies are recommended to ensure the test results reflect that of the patient tested and are available at an additional charge.
4. Order MATCC / Maternal Cell Contamination, Molecular Analysis, Varies on the maternal specimen.
Specimen Type: Extracted DNA
Container/Tube:
Preferred: Screw Cap Micro Tube, 2mL with skirted conical base
Acceptable: Matrix tube, 1mL
Collection Instructions:
1. The preferred volume is at least 100 mcL at a concentration of 75 ng/mcL.
2. Include concentration and volume on tube.
Specimen Stability Information: Frozen (preferred) 1 year/Ambient/Refrigerated
Additional Information: DNA must be extracted in a CLIA-certified laboratory or equivalent and must be extracted from a specimen type listed as acceptable for this test (including applicable anticoagulants). Our laboratory has experience with Chemagic, Puregene, Autopure, MagnaPure, and EZ1 extraction platforms and cannot guarantee that all extraction methods are compatible with this test. If testing fails, one repeat will be attempted, and if unsuccessful, the test will be reported as failed and a charge will be applied. If applicable, specific gene regions that were unable to be interrogated due to DNA quality will be noted in the report.
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 (T576)
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
66569Useful For
Diagnosis of Charcot-Marie-Tooth type 1A or hereditary neuropathy with liability to pressure palsies
Genetics Test Information
This test assesses for large deletions and duplications only.
Special Instructions
Method Name
Dosage Analysis by Polymerase Chain Reaction (PCR)/Multiplex Ligation-Dependent Probe Amplification (MLPA)
Reporting Name
PMP22 Gene, Deletion/DuplicationSpecimen Type
VariesSpecimen Minimum Volume
See Specimen Required
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Varies | Varies | |
Reject Due To
All specimens will be evaluated by Mayo Clinic Laboratories for test suitability.Clinical Information
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.
Reference Values
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 alterations (ie, 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;17(5):405-424
2. van Paassen BW, van der Kooi AJ, van Spaendonck-Zwarts KY, Verhamme C, Baas F, de Visser M. PMP22 related neuropathies: Charcot-Marie-Tooth disease type 1A and Hereditary Neuropathy with liability to Pressure Palsies. Orphanet J Rare Dis. 2014;9:38
3. Li J, Parker B, Martyn C, Natarajan C, Guo J. The PMP22 gene and its related diseases. Mol Neurobiol. 2013;47(2):673-698
4. Bird TD. Charcot-Marie-Tooth Hereditary Neuropathy Overview. In: Adam MP, Feldman J, Mirzaa GM, et al, eds. GeneReviews [Internet]. University of Washington, Seattle; 1998. Updated August 1, 2024. Accessed January 16, 2025. Available at www.ncbi.nlm.nih.gov/books/NBK1358/
5. Chen L, Zhang H, Li C, Yang N, Wang J, Liang J. Literature review of clinical analysis of hereditary neuropathy with liability to pressure palsies. J Neurol. 2024;272(1):41. doi:10.1007/s00415-024-12839-7
6. Chrestian N. Hereditary Neuropathy with Liability to Pressure Palsies. In: Adam MP, Feldman J, Mirzaa GM, et al, eds. GeneReviews [Internet]. University of Washington, Seattle; 1998. Updated August 27, 2020. Accessed January 16, 2025. Available at www.ncbi.nlm.nih.gov/books/NBK1392/
7. Martinez Thompson JM, Klein CJ. Thirty Years Later, Case Closed: A Case of PMP22 Triplication From Anticipation. Mayo Clin Proc. 2016;91(5):687-688. doi:10.1016/j.mayocp.2015.12.019
8. Pisciotta C, Bertini A, Tramacere I, et al. Clinical spectrum and frequency of Charcot-Marie-Tooth disease in Italy: Data from the National CMT Registry. Eur J Neurol. 2023;30(8):2461-2470. doi:10.1111/ene.15860
9. Weterman MA, van Ruissen F, de Wissel M, et al. Copy number variation upstream of PMP22 in Charcot-Marie-Tooth disease. Eur J Hum Genet. 2010;18(4):421-428. doi:10.1038/ejhg.2009.186
10. Zhang F, Seeman P, Liu P, et al. Mechanisms for nonrecurrent genomic rearrangements associated with CMT1A or HNPP: rare CNVs as a cause for missing heritability. Am J Hum Genet. 2010;86(6):892-903. doi:10.1016/j.ajhg.2010.05.001
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)
Day(s) Performed
Varies
Report Available
14 to 21 daysSpecimen Retention Time
Whole blood: 28 days (if available); Extracted DNA: 3 monthsPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.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 |
Testing Algorithm
For information see Hereditary Peripheral Neuropathy Diagnostic Algorithm