face, arms, legs, and trunk. It tends to lessen in the later stages. When the disease occurs in childhood (less than 10% of cases) Chorea is more severe and may coincide with rigidity or muscle stiffness and movement restriction. Both chorea and rigidity interfere with coordination and mobility. Changes in mood are not readily noticeable as they are slow to manifest and can be interpreted as something else (i.e. HD causes depression but so does our society so this symptom often gets overlooked) Anxiety, irritability, rage, mania, and psychosis are also common symptoms.Cognition (the mental process characterized by thinking, learning, and judging) is affected early in the disease and gets worse over time. Individuals will have problems with math, memory, judgment and verbal fluency. It is very difficult for someone with HD to learn a new task, especially in the later stages of development.There currently is neither a cure nor FDA approved medical treatment for Huntington’s disease. The life expectancy is 15 – 20 years after development begins, and though Huntington’s itself doesn’t directly kill the individual, it causes so many functional breakdowns in the body that the person can no longer perform basic physical operations such as swallowing and as such a common cause of death is choking or respitory infection.Biochemistry and Molecular BiologyHuntington disease is caused by the expansion of a polymorphic trinucleotide repeat (CAG)n located in the coding region of the Huntingtin gene. The range of these repeats in normal individuals is 9 to 37, but in HD patients it ranges from 37 to 86 and cases up 150. The human HD gene was cloned to 4p16.3 on chromosome 4 in 1993 by the HD Collaborative Research Group. The gene named IT15( important transcript 15) includes 180-200kb and consists of 67 exons. The HD mutation occurs in the first exon of this gene, which codes for a large 348kd protein named 'huntingtin' (htt). ...
