Huntington Disease (HTT) Genetic Testing (Repeat Expansion)

Casandra

Casandra Test Code LC53584Version 1 (DRAFT)

Performing Lab

Lab LabcorpLab Test ID 620016CPT Code 81271

Huntington Disease (HTT) Genetic Testing (Repeat Expansion)

Clinical Use

Use

Huntington disease (HD) is a neurodegenerative disease of mid-life onset that produces choreic movements and cognitive decline, often accompanied by psychiatric changes. The disease is caused by an expansion of the CAG repeats in 3-5 out of 100,000 individuals. However, the prevalence of HD exceeds 15 per 100,000 in some populations, mostly of Western European origin. Juvenile-onset HD occurs in approximately 5% of affected patients, is rapidly progressive, and presents with rigidity, spasticity, and intellectual decline before the age of 20 years. The symptoms result from the selective loss of neurons, most notably in the caudate nucleus and putamen, and there is currently no effective treatment.

Special Instructions

This test is not available in New York State. A complete Informed Consent must accompany specimens. For additional information, related documents such as consent forms should be downloaded and reviewed.

Limitations

False positive or negative results may occur due to factors such as rare genetic variants, allele dropout, blood transfusions, or mislabeled samples. Repeat sizes greater than the maximum reportable range are noted as greater than the largest reportable repeat size. Specific nucleotide repeat expansions cannot be assessed beyond the described maximum limits, e.g., alleles with more than 100 repeats in the HTT gene.

Test Details