Huntington's Disease Research Paper

Huntington’s Disease is a homozygous dominant neurodegenerative disorder caused by a mutation in the HD gene. The mutation involves the basal ganglia, striatum and cerebral cortex parts of the brain and causes a CAG trinucleotide repetition. This repetition then proceeds to cause involuntary chorea, mood disorders, mental instability, and eventually leads to death. Since this is a relatively new discovery the Huntingtin gene is still mysterious in many ways to researchers. Many new discoveries have been made in regards to the damage that the mutation does to the brain but exactly how it does it eludes the science community. The gene that carries the mutation for Huntington’s disease follows a heterozygous dominant line of inheritance. This
The specific location of the CAG nucleic acid repetition is in the coding region of the first axon of the HD gene. In a normal unaffected human, having the CAG is a natural occurrence and usually repeats about twenty times before it stops. There is not a whole lot known about the normal function of the Huntingtin gene but it is known to be similar to others that have to do with protein interactions. Specifically with proteins that are present in the brain, which is why Huntington’s disease does most of its damage to the brain. (Hopes). With affected Huntington’s disease patients the repetition practically doubles and repeats anywhere around forty to eighty times. If a person experiences any repetition around the doubled rate then there is a complete penetrance for Huntington’s disease. The amount of repeats had been known to correlate with the onset age of this disease, the more repeats there are tend to yield a lower onset age. Even though there is data backing this idea, it is still not yet universally accepted because there is still much research to be done on the topic. This is why it is still very difficult for doctors to predict when the onset range of a person who is affected by Huntington’s disease is, there are just too many variations in cases to make an accurate prediction.
The striatum in the brain is believed to play a large factor in the cause of the symptoms of Huntington’s disease. Its function is to process all of the signals within the neocortex and then pass them to other parts of the basal ganglia and frontal lobes. The parts of the brain that the striatum sends its information to are known for playing a large role in the planning and execution of a person’s bodily movement. Huntington’s disease seems to disrupt the striatum’s pathway in sending its messages, which then interferes with the parts of the brain that control movement. This pathway disruption is what causes the loss of muscle control for those who suffer from the disease. As a person is first affected, the chorea starts off as minor but as the disease progresses more damage is done to the brain, which results in an increase in the severity of symptoms. This is believed to be the reason behind eighty percent of brains belonging to those who have died of Huntington’s disease having significant atrophy to their frontal lobes. Along with a loss of frontal lobe tissue, this disease also causes a loss of striatal tissue, a noticeable amount of one hundred percent of all Huntington’s disease brains examined. Expectedly, on average a brain that has gone through the symptoms of Huntington’s disease is on average smaller than a normal unaffected