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How does an understanding of the disease influence the treatment?

How does an understanding of the disease influence the treatment?

A defect in the gene IT-15 on the 4p16 chromosome is responsible for the hereditary Huntingtons disease. Understanding of the gene in the test subject Drosophila melanogaster allowed scientists to recently prevent the model test subject from becoming blind when the HD gene was introduced into it. This was a result from a drug that has coincidentally been approved by the FDA for cancer treatment. Professor Thomspon states that We believe we have traced one way that the mutation alters chemical pathways to cause the disease. By reversing key changes in these pathways, we have identified a potentially effective way to slow or prevent the disease. Scientists uncovered that the mutant form of the protein huntingtin inhibits the actions of several other proteins. One such protein is the enzyme group acetyltransferase which once inhibited by the mutated huntingtin protein causes nerve damage in the brain. In our body, acetyltransferases act as protein modifiers which increase genetic activity. These enzymes are balanced by HDAC enzymes which reduce genetic activity. And since Huntington Disease patients have a mutated huntingtin protein which results in malfunctioning acetyltransferase enzymes, scientists proposed to reduce HDAC activity to restore balance. So far, this has worked in the Huntington diseased test subject Drosophila melanogaster.

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What is the molecular basis for the disease and what is the biochemical manifestation of the disease?

The molecular basis of Huntingtons Disease is that there is a trinucleotide repeat of CAG in the gene IT-15 of the 4p16 chromosome. Normal people have as many as 26 CAG repeats, however Huntington patients have anywhere from 40 to over 100 CAG repeats. Scientists have found that normally, the younger the patient, the more CAG trinucleotide repeats there are. The biochemical manifestations are a defective huntingtin protein which results in inhibited acetyltransferase enzymes that cause deterioration of the brains nerves. Resulting symptoms are restlessness, choreoathetoid movements, progressive dementia, depression, and the patient becomes weak with muscle spasms and is bed ridden for the next 10-15 years whereupon they die.

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Speculate why the disease is more severe in the offspring of fathers who had the disease than in those whose mother had the disease.

Huntingtons disease is an autosomal dominant gene located on the IT-15 gene of the chromosome 4p16. Being an autosome, the defected gene can be found in either males or females. As per the below website by Debra Collins the disease does not have a higher affecting chance of children with diseased fathers. Thus, males and females have the same chance of having affected children with 50% chance of the child being affected.

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What is the etiology and mechanism of the disease?

Named after Doctor George Sumner Huntington, this disease originated in Western Europe but can now affect people of any race. The disease works from the gene level. The Huntington gene contains a section of C-A-G bases. When there is an excess of these bases (which code for glutamine), Huntington usually develops. Because there are so many glutamines, the Huntington protein folds into a different shape than normal. Huntington interacts with other proteins especially in the brain. Researchers believe that a protein cuts Huntington and the pieces go into a neuron nucleus. This builds up. The true purpose of the clumps of the pieces of the Huntington protein is not clear. What Huntington does is a mystery. It starts before much cell death has occurred and it shrinks the brain.

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