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26016 Huntington Disease, Molecular Analysis (HAD)

Huntington Disease, Molecular Analysis (HAD)
Test Code: HADSO
Synonyms/Keywords
​HD, Huntington Chorea, Chorea, HTT
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.

Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
​Whole Blood ​EDTA Lavender Top Tube (LTT) ​ACD Yellow Top Tube (YTT) ​3 mL ​1 mL
Collection Processing Instructions

​Send specimen in original tube.  Specimen preferred to arrive within 96 hours of draw.

A recent clinical note is required. Testing cannot proceed without this information

Specimen Stability Information
Specimen Type Temperature
​Varies ​ ​ ​Room Temperature (preferred)
​Frozen
​Refrigerate
Interference

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.

We strongly recommend 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 our interpretation of results may occur if information given is inaccurate or incomplete.

A previous bone marrow transplant from an allogenic donor will interfere with testing. Call Mayo Medical Laboratories at 800-533-1710 for instructions for testing patients who have received a bone marrow transplant.

Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Mayo Clinic Laboratories​ ​Monday, thursday ​4-11 days ​Polymerase Chain Reaction (PCR)
Reference Lab
Test 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 Range Information
Performing Location Reference Range
​Mayo Clinic Laboratories ​Normal alleles: <27 CAG repeats
Intermediate alleles: 27-35 CAG repeats
Reduced penetrance: 36-39 CAG repeats
Full penetrance: >39 CAG repeats
Interpretation

​An interpretive report will be provided.

Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
81271
Synonyms/Keywords
​HD, Huntington Chorea, Chorea, HTT
Ordering Applications
Ordering Application Description
​COM Huntington Disease, Molecular Analysis (HAD)
​Centricity Huntington Disease, Molecular Analysis (HAD)
​Cerner Huntington Disease, Molecular Analysis (HAD)
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
​Whole Blood ​EDTA Lavender Top Tube (LTT) ​ACD Yellow Top Tube (YTT) ​3 mL ​1 mL
Collection Processing

​Send specimen in original tube.  Specimen preferred to arrive within 96 hours of draw.

A recent clinical note is required. Testing cannot proceed without this information

Specimen Stability Information
Specimen Type Temperature
​Varies ​ ​ ​Room Temperature (preferred)
​Frozen
​Refrigerate
Interference

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.

We strongly recommend 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 our interpretation of results may occur if information given is inaccurate or incomplete.

A previous bone marrow transplant from an allogenic donor will interfere with testing. Call Mayo Medical Laboratories at 800-533-1710 for instructions for testing patients who have received a bone marrow transplant.

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.

Reference Range Information
Performing Location Reference Range
​Mayo Clinic Laboratories ​Normal alleles: <27 CAG repeats
Intermediate alleles: 27-35 CAG repeats
Reduced penetrance: 36-39 CAG repeats
Full penetrance: >39 CAG repeats
Interpretation

​An interpretive report will be provided.

For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Mayo Clinic Laboratories​ ​Monday, thursday ​4-11 days ​Polymerase Chain Reaction (PCR)
Reference Lab
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
81271
For most current information refer to the Marshfield Laboratory online reference manual.