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Test ID: PNPAN Peripheral Neuropathy Expanded Panel by Next-Generation Sequencing (NGS)

Useful For

Diagnosis of inherited peripheral neuropathies with isolated nerve involvement or associated with other organ system or associated with metabolic syndromes with known causal genes

 

A second-tier test for patients in which previous targeted gene mutation analyses for specific inherited peripheral neuropathy-related genes were negative

 

Identifying mutations within genes known to be associated with inherited peripheral neuropathy, allowing for predictive testing of at-risk family members

Method Name

Custom Sequence Capture and Targeted Next-Generation Sequencing (NGS) followed by Polymerase Chain Reaction (PCR) and Sanger Sequencing when appropriate

Reporting Name

Peripheral Neuro Expanded Panel

Specimen Type

Varies


Shipping 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 Mayo Medical Laboratories 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:

1. 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.

2. Prior Authorization is available for this test. Submit the required form with the specimen.


Specimen Minimum Volume

3 mL

Specimen Stability Information

Specimen Type Temperature Time
Varies Ambient (preferred)
  Frozen 
  Refrigerated 

Clinical Information

Inherited peripheral neuropathies are a relatively common diverse group of disorders with heterogeneous genetic causes. Due to the considerable overlap in the clinical phenotypes of various neuropathies, it is often difficult to distinguish these specific inherited disorders from sporadic, idiopathic, or acquired forms of neuropathy without genetic testing. Based on the pattern of inheritance and nerve conduction studies, there are 3 major categories of inherited peripheral neuropathies with isolated nerve involvement: 1) hereditary motor and sensory neuropathy (HMSN), also referred as Charcot Marie Tooth (CMT); 2) hereditary sensory and autonomic neuropathy (HSAN), or hereditary sensory neuropathy (HSN), if autonomic dysfunction is absent; and 3) distal hereditary motor neuropathy (dHMN). Inherited peripheral neuropathies may also show involvement of the central nervous system (brain or spinal cord), as in hereditary spastic paraplegia (HSP) with neuropathy (complicated form, also referred to as HSMN type 5) or be part of a systemic syndromic or metabolic disorder.

 

Given the considerable phenotypic overlap and the broad genetic heterogeneity of inherited peripheral neuropathies a comprehensive diagnostic genetic test is useful to establish the genetic cause in these clinical groups.

 

The recommended first-tier test to screen for hereditary motor and sensory neuropathy is PMP22 / PMP22, Peripheral Neuropathy, FISH, which assess for large deletions and duplications of the PMP22 gene.

 

See Targeted Genes Interrogated by Peripheral Neuropathy Expanded Panel in Special Instructions for details regarding the targeted genes identified by this test.

Reference Values

An interpretive report will be provided.

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.

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. Klein CJ, Duan X, Shy ME: Inherited neuropathies: Clinical overview and update. Muscle Nerve 2013:48(4):604-622

3. Dyck PJ, Oviatt KF, Lambert EH: Intensive evaluation of referred unclassified neuropathies yields improved diagnosis. Ann Neurol 1981;10(3):222-226

4. Saporta AS, Sottile SL, Miller LJ, et al: Charcot-Marie-Tooth disease subtypes and genetic testing strategies. Ann Neurol 2011;69(1):22-33

Day(s) and Time(s) Performed

Performed weekly, Varies

Analytic Time

10 weeks

CPT Code Information

81260

81325

81403

81404 x 6

81405 x 14

81406 x 10

81407 x 3

81408

81479

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PNPAN Peripheral Neuro Expanded Panel In Process

 

Result ID Test Result Name Result LOINC Value
38195 Result Summary 50397-9
38196 Result In Process
38197 Interpretation In Process
38198 Additional Information 48767-8
38199 Specimen 31208-2
38200 Source 31208-2
38201 Released By No LOINC Needed

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

Testing Algorithm

See Hereditary Peripheral Neuropathies Testing Algorithm in Special Instructions

Forms

1. New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (T576) is available in Special Instructions.

2. Molecular Genetics: Neurology Patient Information in Special Instructions

3. Peripheral Neuropathy Expanded Panel by Next-Generation Sequencing (NGS) Prior Authorization Ordering Instructions in Special Instructions

4. If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/neurology-request-form.pdf

Mayo Medical Laboratories | Genetics and Pharmacogenomics Catalog Additional Information:

mml-inherited-molecular