Bookshelf

Natural history of Huntington disease (HD)

The premanifest period occurs before signs and symptoms of HD are identified and includes presymptomatic and prodromal phases. Presymptomatic individuals are free from signs and symptoms of HD. During the prodromal phase, subtle signs and symptoms may be present prior to the diagnosis of HD, which is usually based on motor symptoms. During manifest HD, chorea may be one of the most prominent features, followed by a slow progression of motor and cognitive impairments. Fine motor impairments (incoordination, bradykinesia, and rigidity) progress more steadily. The normalized CAG age product (CAP) score enables progression of many individuals with different HTT CAG repeat expansion lengths to be plotted on the same graph. Mean disease onset is at CAP score ~100 (typically age ~45 years), but there is substantial individual variability.

Reproduced from Bates et al [2015]