Prevalence of Reduced-Penetrance Huntington Alleles

Should we check for the Huntington disease gene in older patients with chorea?

The CAG trinucleotide repeat on chromosome 4 is known to underpin the occurrence of Huntington disease (HD). To estimate the frequency and penetrance of at-risk CAG repeat alleles within a general population, rather than a disease-based population, researchers assessed CAG repeats in 7315 asymptomatic individuals from British Columbia, the United States, and Scotland. Because 36 to 39 copies of the CAG repeat are associated with older age of HD onset compared with higher copy numbers, the researchers also used their data to estimate the penetrance of 36–39 CAG repeat alleles in people aged ≥65 years in British Columbia.

In the full cohort, 18 cases of ≥36 repeat alleles were identified (1 in 400), and 15 of these were 36–39 repeat alleles — …

Reviewing Author

Michael S. Okun, MD

Disclosures

Consultant/Advisory BoardParkinson’s Foundation; Tourette Association of America

Speaker’s BureauMedscape/WebMD CME, Movement Disorders Society CME, American Academy of Neurology CME

RoyaltiesBooks4Patients; Demos; Cambridge; Taylor and Francis; Robert Rose; Public Affairs

Grant/Research SupportNational Institutes of Health; Parkinson’s Foundation; Tourette Association of America; University of Florida Foundation

Editorial BoardsTremor and Other Hyperkinetic Movements; JAMA Neurology

Leadership Positions in Professional SocietiesParkinson’s Foundation (Medical Advisor)