Huntington Disease

HUNTINGTON DISEASE:

Huntington disease (HD) results in a progressive loss of muscle control characterized by jerky or choric movements, and loss of cognitive function. Onset of the disease symptoms is typically between ages 45 and 65 and are often consistent within the family. However, earlier and juvenile onset are possible. Once the first signs of Huntington disease are detected, there is an inevitable degeneration leading to death 6 to 20 years after onset.

Huntington disease is an autosomal dominant disease resulting from an expansion of a CAG repeat region in the huntingtin gene (chromosome 4p). Unaffected individuals have between 5 and 30 of the CAG repeats. However, an abnormal expansion to 39 or more of the CAG repeats cause the disease. Juvenile onset of Huntington disease typically has expansions of 70 to 120 CAG repeats.

REASONS FOR REFERRAL:

To determine whether an individual with an ataxia has HD.
To differentiate individuals with HD from other ataxias.
Individuals with a family history of HD who want to determine their risk (Pre-symptomatic Protocol)
Families considering future medical and disability insurance needs.
Individuals at risk who wish prenatal diagnosis.
For ambiguous patients, this test may be ordered as part of the Neurological Panel.
Pre-symptomatic testing for individuals at risk for Huntington disease is available under a nationally approved protocol recommended by the Huntington Disease Society of America. This protocol restricts the testing to those 18 years of age or older in the absence of any special medical indications. Please call for information regarding the Huntington Disease Pre-symptomatic Protocol.

TESTING METHODOLOGY:

Fluorescent PCR sizing of the CAG region of the Huntington gene.

SPECIMEN REQUIREMENTS:

Blood EDTA (purple top) tubes:

Newborn: minimum 1-2 mL

Child/Adult: prefer 2 tubes of 3-5 mL

Prenatal testing: Please contact the laboratory for instructions.

A Molecular Genetics Laboratory Test Requisition must accompany the specimen. Contact the Molecular Laboratory at 918-502-1721 to obtain further information.

Confirmatory Testing: A confirmatory testing form signed by the requesting physician MUST accompany the specimen.

Pre-symptomatic Testing requires a specific protocol, as recommended by the HDSA. (see above)

TURNAROUND TIME: 10 working days

CPT CODES: