Huntington Disease (HD) Mutation by PCR
0040018
 
Ordering Recommendation
Diagnostic testing for Huntington disease.
Predictive testing for Huntington disease.
Mnemonic
HD
Methodology
Polymerase Chain Reaction/Fragment Analysis
Performed
Varies
Reported
7-10 days after receipt of fully completed HD consent form
New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
 
Collect
Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).  
Specimen Preparation
Transport 5 mL whole blood. (Min: 3 mL)  
Storage/Transport Temperature
Refrigerated.  
Unacceptable Conditions
 
Remarks
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.  
Stability
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:
Characteristics:
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).
Incidence:
1 in 15,000.
Inheritance:
Autosomal dominant.
Cause:
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.
Methodology:
Chimeric PCR followed by size analysis using capillary electrophoresis.
Analytical Sensitivity and Specificity:
99 percent.
Limitations:
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 recommended for genetic testing. Consent forms are available online at www.aruplab.com.

See Compliance Statement C: www.aruplab.com/CS
Phenotype Number of CAG Repeats
Normal allele Less than or equal to 26
Mutable normal allele 27-​35
HD allele with reduced penetrance 36-​39
HD allele Greater than or equal to 40
Note
CPT Code(s)
81401
Components
Component Test Code*Component Chart Name
0050604Huntington Disease (HD) Allele 1
0050606Huntington Disease (HD) Allele 2
0050607Huntington Disease (HD) Interpretation
2001353Huntington Disease (HD) - Specimen
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, contact interface support at interface.support@aruplab.com.
Cross References