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Huntington’s disease is an autosomal dominant (Harper et al, 1991) neurodegenerative disorder characterized by involuntary movements, cognitive loss, and psychiatric problems as described by Martin and Gusella (1986). These symptoms are related to the death of medium spiny projection neurons in the caudate nucleus, putamen, and the cortex (Reiner et al, 1988). In later stages of the disease, even areas such as the hippocampus and hypothalamus gets affected as well (Kassubek et al, 2004). Huntington’s disease has a prevalence rate of approximately 1 in 10,000 Caucasian populations (Harper et al, 1991). Patients with Huntington’s disease most typically display a choreic movement disorder involving involuntary writhing movements observed by George Huntington himself. The age of onset of Huntington’s disease seem to be normally distributed around the average age of 35 to 42, with small number of cases developing in patients younger than 20 years of age or older than 60 years of age (Andrew et al, 1993). The majority of juvenile patients, whose disease onset are at age 20 years or less, have inherited the paternally defected gene (Andrew et al, 1993). Patients usually died within 15 to 20 years of disease onset. Gusella et al (1983) first determined the location of the genetic mutation in Huntington’s disease to be the short arm of chromosome 4. It was after another 10 years did the researchers of The Huntington’s Disease Collaborative Research Group (1993) able to discover that a gene in chromosome 4 containing a trinucleotide repeat of CAG was abnormally expanded in diseased individuals. The IT15 (interesting transcript 15) gene, dubbed the huntingtin gene by the group, codes for the huntingtin gene. This CAG repeat, which translates into a poly-glutamine stretch, is highly polymorphic among the population ranging from 11 to 34 copies on normal individuals. However, in individuals with Huntington’s disease it expanded to more than 42 repeats and increasing to...
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