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 (PCR)/Fragment Analysis




7-10 days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation

Lavender (EDTA), pink (K2EDTA), or yellow (ACD solution A or B).

Specimen Preparation

Transport 3 mL whole blood. (Min: 1 mL)

Storage/Transport Temperature

Refrigerated. Also acceptable: Ambient.

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.


Room temperature: 1 week; Refrigerated: 1 month; Frozen: Unacceptable

Reference Interval

Interpretive Data

Refer to report

Allele type
Number of CAG Repeats
Normal allele Less than or equal to 26
Mutable normal (intermediate) allele 27-35
HD allele with reduced penetrance 36-39
HD allele with full penetrance Greater than or equal to 40

Compliance Category

Laboratory Developed Test (LDT)


Hotline History


CPT Codes



Component Test Code* Component Chart Name LOINC
0050604 Huntington Disease (HD) Allele 1 49637-2
0050606 Huntington Disease (HD) Allele 2 49638-0
0050607 Huntington Disease (HD) Interpretation 50621-2
2001353 Huntington Disease (HD) - Specimen 31208-2
* 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.


  • HD genetic testing
  • HTT genetic testing
Huntington Disease (HD) Mutation by PCR