The Role of Polyglutamine Expansions in Huntington’s Disease Essay

Huntington’s disease (HD) is a neurodegenerative dominant disorder caused by the expansions of polyglutamine in the gene encoding for Huntington’s protein. It is a developmental autosomal brain disorder that affects muscle coordination, emotional and personality problems. As well as subcortical dementia, further leading to cognitive decline this is all related with selective neuronal cell death mainly associated in the striatum and cortex (Scherzinger et al., 1997). HD causes emotional problems, uncontrolled movements and the loss of thinking ability. It can lead to disability and death from the illness. There are two forms of this disease: adult-onset and early-onset (juvenile). Adult onset is by the far most common for HD; symptoms develop between the ages of mid 30s/40s, an individual will live an average of 20 years after symptoms and signs begin. Premature signs and symptoms are depression, involuntary movements, trouble learning new information, poor coordination; this can all progress very severely. The development of pre-disease symptoms into twitching or jerking is referred as Chorea. HD can be referred to Huntington Chorea. Although adult onset is more common disorder, juvenile form, defined by the onset of signs and symptoms before the age of 21 years, this occurs in about 7% of HD cases. (Nance, 2001) Juvenile onset has similar symptoms however the disease progresses more quickly compared to the adult onset form. Gente (1985) results showed findings by others, that the most juvenile-onset patients inherit the gene from their fathers and that the late-onset form is more frequently inherited from affected mothers. HD occurs due to CAG/polyglutamine(polyQ) expansions, in the first exon of a gene encoding a la... ..., C. and Bates, G, P. (2004). Huntingtin and the molecular pathogenesis of Huntington’s disease. EMBO reports 5. 958-963 Nance, M, A. and Myers, R, H. (2001) Panov, A, V., Gutekunst, C., Leavitt, B, R., Hayden, M, R., Burke, J, R., Strittmatter, W, J. And Greenamyre, J, T. (2002) Early mitochondrial calcium defects in Huntington’s Disease are a direct effect of Polyglutamines. Nature neuroscience. Volume 5 no 8 Ross, C, A. (2002). Polyglutamine Pathogenesis: Emergence of Unifying Mechanism for Huntington’s Disease and Related Disorders. Neuron, Vol. 35,819-822. Scherzinger, E., Lurz, R., Turmaine, M., Mangiarini, L., Hollenbach, Birgit., Hasenbank, R., Bates, G, P., Davies, S, W., Lehrach, H and Wanker, E, E. (1997). Huntington-Encoded Polyglutamine Expansions Form Amyloid-like Protein Aggregates In Vitro and In Vivo. Cell, Vol.90, 549-558. Zhang,