Sign in →

Test ID HAD Huntington Disease, Molecular Analysis, Varies


Shipping Instructions


Specimen preferred to arrive within 96 hours of collection.



Necessary Information


Molecular Genetics: Neurology Patient Information or a recent clinical note is required. Testing cannot proceed without this information.



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 whole blood specimen in original tube. Do not aliquot.


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:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen.

Secondary ID

35452

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 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.

Cautions

For predictive testing, it is important to first document the presence of a CAG-repeat amplification in the HTT gene in an affected family member to confirm that molecular expansion is the underlying mechanism of disease in the family.

 

It is strongly recommended that patients undergoing predictive testing receive genetic counseling both prior to testing and after results are available.

 

Predictive testing of an asymptomatic child is not recommended.

 

Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in the interpretation of results may occur if information given is inaccurate or incomplete.

Day(s) Performed

Wednesday

Report Available

7 to 11 days upon receipt of sufficient clinical information for testing

Performing 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

81271-HTT (huntingtin) (eg, Huntington disease) gene analysis; evaluation to detect abnormal (eg, expanded) alleles

NY State Approved

Yes