Huntington Disease (HD) Mutation by PCR
Ordering Recommendation

Diagnostic confirmation for Huntington disease (HD) in a symptomatic individual. Presymptomatic testing for adults with a family history of HD.

Polymerase Chain Reaction/Fragment Analysis
7-10 days after receipt of fully completed HD consent form
New York DOH Approval Status
This test is New York DOH approved.
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B). 
Specimen Preparation
Transport 5 mL whole blood. (Min: 3 mL) 
Storage/Transport Temperature
Unacceptable Conditions
A completed HD specific consent form, signed by the patient (or legal guardian) and physician, is required for all specimens. Testing for patients under the age of 18 years or fetal specimens is not offered. Presymptomatic patients are strongly encouraged to be tested through a counseling program approved by the Huntington Disease Society of America at (800) 345-4372. Call Genetics Processing with additional questions at 800-242-2787 ext 3301. 
Ambient: 72 hours; Refrigerated: 1 week; Frozen: 1 month 
Reference Interval
Negative: This individual has two normal alleles; and therefore, is neither a carrier nor will be affected with Huntington disease.
Interpretive Data
Background Information for Huntington Disease (HD) Mutation by PCR:
Neurodegenerative disorder causing progressive cognitive, motor, and psychiatric disturbances typically beginning at 35-44 years of age
(Although, 5 percent are affected as juveniles and 25 percent affected after age 50).
1 in 15,000.
Autosomal dominant.
Expanded number of CAG repeats in the HD gene (27-35 repeats-unaffected, intermediate; 36-39 repeats-reduced penetrance; 40+ repeats-affected, full penetrance).
Clinical Sensitivity and Specificity:
99 percent.
Chimeric PCR followed by size analysis using capillary electrophoresis.
Analytical Sensitivity and Specificity:
99 percent.
Other neurodegenerative disorders will not be detected. Rare, previously unreported variants may interfere with PCR amplification. Diagnostic errors can occur due to rare sequence variations.

Counseling and informed consent are required for Huntington Disease genetic testing. Consent forms are available online at

Number of CAG Repeats
Normal alleleLess than or equal to 26
Mutable normal allele27-35
HD allele with reduced penetrance36-39
HD alleleGreater than or equal to 40

Compliance Statement C: For human genetic inheritable conditions and mutations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Hotline History
View Hotline History
Component Test Code*Component Chart NameLOINC
0050604Huntington Disease (HD) Allele 149637-2
0050606Huntington Disease (HD) Allele 249638-0
0050607Huntington Disease (HD) Interpretation50621-2
2001353Huntington Disease (HD) - Specimen31208-2
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
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