Confirmation of subtle motor changes among presymptomatic carriers of the Huntington disease gene.

Abstract

HUNTINGTON disease (HD) is an autosomal dominant, neurodegenerative disorder characterized neuropathologically by the loss of medium-sized spiny neurons in the neostriatum. Huntington disease is caused by an increased number of triplet (CAG) repeats in the HD gene, which is on chromosome 4.¹ Typically, individuals with HD have 38 or more CAG repeats. A negative correlation between age at HD onset and number of CAG repeats has been observed, with patients with juvenile-onset HD having the greatest number of CAG repeats.¹ The clinical implication of an intermediate allele with 32 to 37 repeats is ambiguous, as such an allele may confer variable penetrance or meiotic instability.²