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Test ID: HAD Huntington Disease, Molecular Analysis

Useful For

Molecular confirmation of clinically suspected cases of Huntington disease (HD)

 

Presymptomatic testing for individuals with a family history of HD and a documented expansion in the HTT gene

Method Name

Polymerase Chain Reaction (PCR)

Reporting Name

Huntington Disease Analysis

Specimen Type

Varies


Specimen Required


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: Specimen preferred to arrive within 96 hours of draw.


Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Varies Ambient (preferred)
  Frozen 
  Refrigerated 

Clinical Information

Huntington disease (HD) is an autosomal dominant progressive neurodegenerative disorder caused by a CAG repeat expansion in the HTT gene. HD is associated with cognitive impairment leading to dementia and a wide range of neuropsychiatric problems including apathy, depression, anxiety, and other behavioral disturbances. Additionally, affected individuals typically develop extrapyramidal symptoms (eg, dystonia, dysarthria, chorea, gait disturbance, postural instability, oculomotor dysfunction).

Reference Values

Normal alleles: <27 CAG repeats

Intermediate alleles: 27-35 CAG repeats

Reduced penetrance: 36-39 CAG repeats

Full penetrance: >39 CAG repeats

An interpretive report will be provided.

Interpretation

An interpretive report will be provided.

Clinical Reference

1. American College of Medical Genetics/American Society of Human Genetics Huntington Disease Genetic Testing Working Group: Laboratory guidelines for Huntington disease genetic testing. Am J Hum Genet 1998;62:1243-1247

2. Potter NT, Spector EB, Prior TW: Technical standards and guidelines for Huntington disease testing. Genet Med 2004;6:61-65

Day(s) and Time(s) Performed

Tuesday, 10 am

Specimens received Tuesday through Saturday will be processed for the run starting on following Tuesday. Specimens received on Monday will be set up a week from the following Tuesday.

Analytic Time

4 days upon receipt of sufficient clinical information for testing.

CPT Code Information

81401-HTT (huntingtin) (eg, Huntington disease), evaluation to detect abnormal (eg, expanded) alleles

LOINC Code Information

Test ID Test Order Name Order LOINC Value
HAD Huntington Disease Analysis 21763-8

 

Result ID Test Result Name Result LOINC Value
52885 Result Summary 50397-9
52886 Result 53782-9
52887 Interpretation 69047-9
52888 Reason for Referral 42349-1
52889 Specimen 31208-2
52890 Source 31208-2
52891 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.

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. 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