FINAL VERSION Genetics Assignment

 

All About Huntington’s Disease

Huntington's disease (or HD) is an inherited brain disorder that affects emotional, cognitive and motor abilities. It is found in all regions of the world but is more prevalent in people of Western European descent. There is an equal chance of both men and women inheriting this genetic disorder. Asian and African countries have a lower rate of occurrence. The U.K. and some isolated regions around the world have the highest rates.

The physical symptoms of this disorder make it easily distinguishable from other disorders such as dementia. These include nervous activity or rigid muscles, restlessness, clumsiness or lack of coordination and difficulty with everyday skills. These worsen over time. Intellectual and emotional signs also develop gradually but are usually only noticed after the physical signs. Emotional signs do not usually directly single out the possibility of HD.

Huntington's disease is inherited in an autosomal dominant pattern. Those who inherit the faulty gene will eventually get the disease as it is genetically dominant. A parent with a mutation in the HD gene has a 50 percent chance of passing the disease to their children. This probability varies in different cases. (Diagram on the right:)

Effects of HD can become apparent at any age from infancy to later in life, but usually begin between 30 and 50 years of age.It is usually difficult to predict how old an affected person will be when they develop the condition if they inherit the abnormal gene.

There is no cure for HD. This is similar to many of these common disorders. The progression of the diseasecannot beslowed by treatment. Patients may become more comfortable through the various types of medications available. Depression and anxietymay beeased. Involuntary movements can be controlled. Physical or speech therapy is one method of improving the quality of life that HD patients lead.

Chromosome number four carries the faulty gene that causes Huntington's disease. The normal copy of the gene produces a protein called huntingtin. Normally, the coding region of this gene contains the DNA sequence "CAG" repeated again and again. The number of times this triplet is repeated varies from person to person, ranging from 10 to 26 times. People with HD have an abnormally high number of these CAG triplets, approximately 40 or more. This area is larger than normal and produces a mutant form of huntingtin. The basal ganglia and parts of the cortex located in the brain are very sensitive to the effects of the abnormal huntingtin. This makes them function poorly and eventually die. The brain cells of HD patients also accumulate clumps of protein that somehow become toxic, resulting in cell death. The brain normally sends messages through the basal ganglia and cortex to control thinking and movement. By having this important function gradually impaired, the very serious symptoms of HD appear.

Personal Opinion Box

Research and knowledge on Huntington’s chorea seems to be varied depending on the country. Perhaps one of the reasons why there still is no cure that exists for HD is because only countries with large populations of Europeans and Americans are trying to come up with something. It is related to a dominant gene, unlike colour blindness, which is recessive and doesn’t affect females as much. Most forms of chorea are usually described as this disease. This disease was known several decades ago but the cause was unknown. Only recently has genetic research found the gene of this disease and created the possibility of treating or curing this chorea.Much improvement is required for all genetic diseases.

Many genetic disorders and hereditary diseases have to be endured for a lifetime. Common cases of HD can at least allow the person to spend their childhood normally. Most people with very apparent disorders rarely ever fully connect and integrate into society. Disabilities may have been accepted but disorders are still an issue. After all, we don’t see people with HD working in offices or anywhere, especially as HD affects everything that we need to live and work. All we can do is be thankful that we live and work and do the things we do in the way we do them usually.

The scientists in every country only research and find cures for popular problems or common disorders of their country. As multicultural regions increase and the world becomes more connected through the Internet and other ways, we must ensure that there is a balanced amount of research on all issues.

^References

^{Australian Huntington's Disease Association (NSW) Inc. 2016, What Are The Symptoms Of Huntington's Disease (HD)? http://www.huntingtonsnsw.org.au/information/hd-facts/symptoms, (accessed 11 March 2016).}

^{“ハンチントンブドウ病” 2013, ブリタニカ国際大百科事典 小項目電子辞書版, Britannica Japan Co., Ltd.}

^{“Huntington’s Chorea” 2011, Britannica Concise Encyclopedia, Encyclopædia Britannica, Inc.}

^{“ハンチントンブドウ病” 2013, 百科事典 マイぺディア 電子辞書版, Hitachi Solutions Business, Ltd.}

^{University of Utah 2016, Huntington’s Diseasehttp://learn.genetics.utah.edu/content/disorders/singlegene/hunt/, (accessed 11 March 2016).}

^{U.S. National Library of Medicine 2016, Huntington disease https://ghr.nlm.nih.gov/condition/huntington-disease, (accessed 11 March 2016).}

^{Wikipedia 6 March 2016, at 13:50,Huntington’sdiseasehttps://en.wikipedia.org/wiki/Huntington%27s_disease, (accessed 11 March 2016).}

Noah Nishihara T09