Huntington´s disease characterised by chorea beacuse of vouluntary body movement such as random movement which is uncontrolable, this due to gene mutation.The Huntingtin protien (HTT) codes by Huntingtin gene (HTT) in all human, section of this gene called “trinucleotide repeat“ ( Francis O Walker,2007) and differentiate from person to another by the length which is varies.
A dishonarable gen may produce if the reprat in a fine gene because of dynamic mutation which is rise the repeat count, and mutate form of protien is produce known as mutant Huntingtin protein when the length of the repeated part reaches into a specific threshold. The various of the work of this protien cause the symptomes of the disease. The mutation of (HTT) allele in a human cause the disesae. The (HTT) gene find on chromosome 4 and contain “a sequence of three DNA bases cytosine-adenine-guanine (CAG) called trinucleotide repeat“(Francis O Walker,2007) these three letters code the amino acid glutamine and the sequence of this amino acid produce a series of glutamin called a´´ polyglutamine tract (or polyQ tract), and the repeated part of the gene(polyQ region) “ (Masahisa Katsuno, et al,2008).Individuals have less than 36 repeated glutamin in the repeated part of the gene, this leads to output “cytoplasmic protein Huntingtin“(Francis O Walker,2007).
Increase or decrease of this chain of glutamine produce a protien which has various property, this various form, called mutant huntingtin (mHTT), which rise the degeneration rate of specific types of neurons in the brain. The nerve cell affected by this gene mutation such as the cerebral cortex it´s function is thinking and action, and basal ganglia it´s function is movement, motor control, emotion and behavior. When those area of the brain affected cause some changes such as uncontrolable movement of the body, emotional and mental change. (Francis O Walker,2007)and(wikipedia).
The early symptomes of Huntington´s disease are change of personlity like humor, physical change, unstable walk and uncommon behaviour ( Adam MP,et al,1998). Early symptoms are related to the work of “ the striatum and its cortical connections“ ((Francis O Walker,2007)and(wikipedia) which involve in body movement, emotion and behavior.