The Pathophysiology Of Huntington 's Disease

The genetic disorder is caused by a mutation in the DNA segment CAG found in chromosome 4 which results nerve cell death. Phenotypic characteristics include gradual motor dysfunction, psychological issues that correlate to degeneration of metal health, and cognitive degeneration. Studies on transgenic mice have allowed a better understanding of the proteins that relate to Huntington’s

Huntington's Disease is a genetic autosomal disorder which effects the brain. It affects about 1 in 20,000 individuals. The symptoms of the disease do not start to occur until after or around 40 years of age. With the onset of the disease the patient starts to gradually deteriorate intellectually, this deterioration also causes involuntary movements. Scientists have only recently found the section of the gene which causes Huntington's disease, and this is allowed them to devise pre-symptomatic tests. However, a cure for the disease is yet to be found.

Huntington’s disease begins affecting the organs, it destroys the function of the multiple roles of the nervous system and the brain cells. The disease causes advanced deterioration and loss of brain cells, and contributes to a devastating loss of motor functions followed by advanced cognitive and intellectual impairment.

At present, there is no cure for the disease, but dynamic progress has been made as researchers explore this illness. HD is inherited as an autosomal dominant condition. In March 1993, scientists realized that HD is caused by a mutation in a gene located on chromosome 4. This gene has a unique genetic sequence for CAG (cytosine-adenine-guanine) and codes for the amino acid glutamine, a building block for the huntingtin pr otein. Normal individuals have this sequence duplicated from 11 to 40 times in their genetic coding without having symptoms of HD. However, individuals with the disease have from 40 up to 100 repeated CAG segments. Juvenile Huntington's Disease occurs wit h 60 or more repeats, linking the longer chains of CAG sequences to earlier and more aggressive onset of the disease.

Huntington’s disease is an autosomal, dominant inherited disorder caused by a polyglutamine expansion at the amino-terminal on the huntingtin protein. It causes a progressive degeneration of spiny nerve cells in the striatum and cortex of the brain, impairing a person’s functional and cognitive abilities. Polyglutamine repeats of 36 are found to be non-threating but sequences containing an additional two or three repeats are associated with Huntington’s disease.

The HEXA gene provides instruction for making part of an enzyme called beta-hexosaminidase A, which plays a very critical role in the brain and spinal cord. This enzyme is found in the lysosomes, which are the structures in cells that break down toxic substances and their job is that of a recycling center. Beta-hexosaminidase A helps break down a fatty substance called GM2 ganglioside. The mutations in the HEXA gene disrupt the activity of beta-hexosaminidase A, which prevents the enzyme from breaking down GM2 ganglioside. As a result, this substance accumulates to toxic levels, particularly in the neutrons in the brain and also the spinal cord. Damage by the buildup of GM2 ganglioside leads to the destruction of the neurons; Causing signs and symptoms of Tay-Sachs disease.

Sixty percent of patients with DMD have a dystrophin gene which holds a deletion (Bulman et al. 457). Another six to ten percent of patients have a dystrophin gene which contains a duplication of one or more exons (Bulman et al. 457). Along with these mutations, other mapping techniques have been used to distinguish further disruptions in the dystrophin gene which seem to cause DMD. Western blotting techniques have been used to identify nonsense mutations on the dystrophin gene (Bulman et al. 458). Polymerase chain sequencing has been used to find a mutation in exon 26 (Bulman et al. 458). Southern analysis revealed that another gene problem which leads to DMD is a premature chain termination, which results in a truncated dystrophin protein (Clemens et al. 1781). These are all mutations found in patients with DMD, which shows that there are various ways the dystrophin gene can be affected. Each of these mutations cause a problem in that they do not function correctly when coding for the protein dystrophin.

4. “Huntington Disease - Genetics Home Reference.” U.S. National Library of Medicine, National Institutes of Health, ghr.nlm.nih.gov/condition/huntington-disease.

Huntington’s disease is caused by a mutation in the gene for a protein called Huntingtin. The genetic mutation results in the building blocks of DNA (cytosine, adenine, and guanine) to be replicated many more times than in an average individual. As a result, Huntington’s disease breaks down brain cells, or neurons, specifically located in the primary motor cortex regions of the brain, but can effect other brain areas

An increase in the size of the CAG segment leads to the production of an abnormally long version of the huntington protein. The elongated protein is cut into smaller, toxic fragments that bind together and accumulate in neurons, disrupting the normal functions of these cells. The dysfunction and eventual death of neurons in certain areas of the brain underlie the signs and symptoms of Huntington

Huntington's disease is an autosomal dominant disorder, which is found on the # 4 chromosome. George Huntington discovered it in 1872. It mainly has an effect on the nervous system. There are around 210,000 bases between D4S180 and D4S127. The disease itself is found in 2% of people in their childhood, and in 5% of the people they were older then 60. (Miller p 16) In the majority of the affected people the disease is detected between the ages of 35-45. In males the disease begins around the time of their childhood. However, in females it begins later in life. This severe symptom has a tendency for the condition to worsen as it is passed on from generation to generation. Huntington’s disease is paternally

Huntington's disease is a genetic disease that causes nerve cells in the brain to deteriorate over time, leading patients to suffer from involuntary movements, emotional disturbances, and cognitive decline. The disease is caused by the mutation of a single gene located on chromosome four. The faulty gene, which codes for a protein called huntingtin, can have anywhere from thirty to fifty more repeats of the CAG codon than a healthy gene. The function of huntingtin is unknown, but an over-abundance of it is confirmed to be the cause of Huntington's disease. Genetic testing and diagnosis for Huntington's disease usually focuses on analyzing blood tests from both the individual and a family member to count the number of CAG repeats encoded in

The HTT gene codes for the manufacturing of the protein huntingtin. It is not currently known what huntingtin is directly necessary for, but it seems to play a role in the proper function of nerves in the brain. Huntington’s Disease is caused by a mutation in the CAG trinucleotide repeat found inside the HTT gene. In people without the disease, the CAG repeats only about 25 times. People with Huntington’s Disease have anywhere from 35 to 120 CAG repeats within the HTT gene. An abnormal number of repeats forces the huntingtin protein to be formed longer than normal. Pieces of these proteins eventually break off and stick to each other to create clumps of protein that begin to gather in neurons in the brain. Eventually, this leads to total blockage and results in neuron death. As with most genetic tests, the testing for Huntington’s Diseases is about 99% accurate. Almost every patient with over 35 CAG repeats will develop Huntington’s Disease at some point in their lifetime (Huntington

Huntington disease (HD) is a genetic disorder characterized by the progressive loss of neurons in the brain. It is caused by expansion of CAG repeats in exon 1 of the huntingtin gene, affecting initially the striatum and progressively the cortex. OS is known to play a role in this disease by promoting mutant Huntingtin aggregation and mutant Huntingtin-dependent cell death by mimicking proteasomal malfunction [24]. Several laboratories have demonstrated the existence of oxidative damage in HD brains [30–33] and those antioxidants slow down disease progression [34]. In HD, the initial cause of oxidative insult is the presence of mutant Htt, which has been shown to increase levels of ROS in neuronal and nonneuronal cells [18]. The level of 8-hydroxydeoxyguanosine,

2005). This is significant because the location of the gene could have different effects on the mitochondria and the neuron itself. The experiment used Western blotting as the main method of completing the study, and used mice as subjects (in vitro and in vivo experiments). The findings were that SOD1 localizes more in the brain mitochondria than in the liver, and the SOD1 are inside and on the surface of the mitochondria in the spinal cord (Vijayvergiya et al. 2005). The results suggest that damage to mitochondria may trigger the start of amyotrophic lateral sclerosis, and this study could provide an insight to the specificity of neuron degeneration. With the fact that SOD1 was more in the brain and spinal cord than anywhere else, the central nervous system is affected and the activities of the body are at risk. This analysis intended to discover where mutant SOD1 combines in the mitochondria of the brain and spinal cord, and how this might contribute to selective neuron death (Vijayvergiya et al.