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Test ID: HMNP Hereditary Motor Neuropathy Panel by Next-Generation Sequencing (NGS)

Useful For

Diagnosing distal hereditary motor neuropathy (dHMN) associated with known causal genes

 

Second-tier testing for patients in whom previous targeted gene mutation analyses for specific inherited hereditary motor neuropathy-related genes were negative

 

Identifying mutations within genes known to be associated with inherited hereditary motor 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

Hereditary Motor Neuropathy 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.

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

1 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. Based on the pattern of inheritance and nerve conduction studies, inherited peripheral neuropathies with isolated nerve involvement can be divided into major categories. Distal hereditary motor neuropathies (dHMN) are one of the major categories of peripheral inherited neuropathies and are characterized by length-dependent, slowly progressive motor neuropathies with variable nerve conduction velocities. The clinical phenotype is variable, but includes progressive weakness and atrophy of the distal muscles, foot deformities, and decreased reflexes. There is significant phenotypic overlap with hereditary motor sensory neuropathy (HMSN), also known as Charcot-Marie-Tooth (CMT); however, sensory loss is usually absent in dHMN. dHMN are subdivided into 11 subtypes based on inheritance pattern and clinical features and include types 1-7, dHMN plus pyramidal signs, X-linked, congenital distal SMA, and Jerash type.

 

Given the considerable phenotypic and genetic heterogeneity of dHMN, a comprehensive diagnostic genetic test is helpful to establish the genetic cause in this group of inherited neuropathies.

 

See Targeted Genes Interrogated by Hereditary Motor Neuropathy 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. Rossor AM, Kalmar B, Greensmith L, et al: The distal hereditary motor neuropathies. J Neurol Neurosurg Psychiatry 2012:83(1):6-14

Day(s) and Time(s) Performed

Performed weekly, Varies

Analytic Time

10 weeks

CPT Code Information

81403

81404 x 2

81405 x 2

81406 x 2

81479

LOINC Code Information

Test ID Test Order Name Order LOINC Value
HMNP Hereditary Motor Neuropathy Panel In Process

 

Result ID Test Result Name Result LOINC Value
38209 Result Summary 50397-9
38210 Result In Process
38211 Interpretation In Process
38212 Additional Information 48767-8
38213 Specimen 31208-2
38214 Source 31208-2
38215 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. Hereditary Motor Neuropathy Panel by Next-Generation Sequencing (NGS) Prior Authorization Ordering 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:

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