HUNTINGTON'S DISEASE AND OTHER CHOREAS

Abstract

Dentatorubral-pallidoluysian atrophy (DRPLA) is an autosomal dominant neurodegenerative disorder resulting from an unstable trinucleotide CAG repeat in a gene on chromosome 12. The DRPLA gene encodes atrophin-1, a protein with unknown function. The length of the CAG repeat expansion is inversely correlated with the age of disease onset [98] and may have a considerable effect on the disease milestones and prognosis in DRPLA patients [99]. The disease is rare in Caucasians and more prevalent in Japanese population (0.7/100,000 people) [100]. The usual age at onset is in the third or fourth decade, although early-onset cases (age < 20) have been described.