Commentary: Huntington disease in a nonagenarian mistakenly diagnosed as normal pressure hydrocephalus.

Huntington disease in the very elderly patient described by Dennhardt and LeDoux in this issue of the Journal of Clinical Neuroscience (J Clin Neurosci 2010;17:1066-67) may have been unrecognised before diagnostic genetic testing. Huntington disease in this age group poses significant counselling challenges as some members of up to four generations may have inherited the mutation. In late onset patients gait disorder rather than chorea may be the most prominent feature at presentation. The range of phenotypic variation is evolving.