Huntington’s Disease: Causes, Symptoms, Diagnosis, And Treatment

Genetic disease refers to a disease caused by genetic factors such as genes or chromosomes. In a narrow sense, it refers to a disease in which a specific gene is inherited from a parent, and in a broad sense means a disease in which genetic factors are involved. There are many different genetic inheritance types such as single gene inheritance, multifactorial inheritance, chromosome abnormalities, mitochondrial inheritance. Single gene inheritance is also known as mendelian or monogenic inheritance. This genetic inheritance is caused by changes or mutations in the DNA sequence of a single gene. Multifunctional inheritance is known as a complex or polygenic generation. Multiple factorial inheritances are caused by environmental factors and mutation combinations of several genes. Chromosome aberrations are a distinct structure consisting of DNA and protein, located in the nucleus of each cell. Since chromosomes are transporters of genetic material, chromosome numbers or structural abnormalities can lead to disease. Mitochondrial inheritance is a gene caused by mutations in mitochondria's non-chromatic DNA. Mitochondria are small circular or rod-shaped cell organs that are involved in cell respiration and are found in the cytoplasm of plant and animal cell. Of these, Huntington's disease is a typical disease caused by single gene inheritance. Huntington's disease, which is often called HD, is a genetic disorder of the central nervous system. Huntington's disease usually occurs in adulthood and can cause a wide variety of symptoms. Symptoms of Huntington's disease usually occur between the ages of 30 and 50. However, the timing of this disease can start much earlier or much later. Although people are the same family, the symptoms of the disease vary from person to person. It aims to the essay that explains information such as the cause, symptoms, and diagnosis of Huntington's disease and indicates how to treat the disease.

Huntington's disease is an inherited disease in which a host destroys or degrades neurons in neurons in certain parts of the brain. American physician George Huntington wrote his first thorough account of Huntington's disease in 1872 and said it was a 'choreography' to highlight some of Huntington's main features. Chorea is derived from the word 'dancing' in Greek and depicts an unobtrusive dance-like movement seen by people with HD. The genetic characteristics of HD help distinguish it from other types of choreographies that are infectious, metabolic, or cause hormones. Understanding the genetic characteristics of HD eventually led modern researchers to pinpoint the cause of the disease. In other words, a mutation or a single gene is a misspelling.

Huntington's disease (HD) is a hereditary genetic disorder that is inherited as an autistic superiority feature because of the expansion of tritiated repeats in the chromosome 4p16.3 gene. Mutations in the HTT gene cause Huntington's disease. HTT mutations that cause Huntington's disease include DNA segments known as CAG trinucleotide repeats. This segment consists of three DNA building blocks (cytosine, adenine, guanine) that appear multiple times in succession. Generally, the CAG segment repeats within the gene 10 to 35 times. For people with Huntington's disease, the CAG segment repeats from 36 to 120 times. People with 36 to 39 CAG repeats may or may not cause signs and symptoms of Huntington's disease. On the other hand, people with more than 40 iterations almost always fail. As the size of the CAG segment increases, an abnormally long version of Huntingtin protein is produced. Elongated proteins bind to each other and are cleaved into smaller, more toxic pieces that accumulate in neurons and hinder the normal function of these cells. 

Two clinical subtypes of HD are distinguishable by age at onset. Adult Onset Huntington's Disease (AOHD) usually tends to occur between 35 and 50 years of age in individuals who repeatedly receive more than 39 triple nucleotides in HTT, but rarely more than 60 youth HD (Judi HD) It is defined as the previous presentation and is generally reported as the highest because there are more than 60 CAG iterations in the HTT (Latimer et al., 2017). Adolescent HD is inherited in a self-organizing manner, which means that a single copy of the transformed gene in each cell is sufficient to cause disability. The affected person usually inherits the altered gene from one affected parent. As the altered HTT gene is transmitted from one generation to the next, the size of the CAG trinucleotide repeat that is responsible for HD often increases in size. Generally, the higher the number of repetitions, the more often the initial symptoms and symptoms are related. This phenomenon is known as anticipation. In most cases, children with adolescent HD inherit an extended CAG trinucleotide repeat from their father but occasionally inherit it from their mother.

According to Sulaiman (2007), the common symptoms of Huntington's disease are unmanageable movements, unbalanced walking, difficulty in swallowing something, difficulty in thinking, and personality changes. HD is a major symptom of mobility impairment, cognitive impairment, and mental impairment. Movement disorders associated with Huntington's disease can include both unconscious exercise problems and involuntary movements, such as muscular problems such as inertial or textural movements, stiffness, or muscle contractions. A cognitive disorder associated with Huntington disease is a lack of awareness of your actions and abilities, slow or slow processing of thought or 'searching' words, and difficulty learning new information. The most common mental illness associated with Huntington's disease is depression. This is not simply a response to the diagnosis of HD. Instead, depression appears to be caused by brain damage and consequent changes in brain function. Another example is social withdrawal or insomnia.

The most notable sign between the two forms of HD is that many people with adolescent HD do not experience choreography that is very commonly associated with adult-onset forms. Instead of showing chorographical dancing, the affected children are often rigid and rigid. Generally, children younger than the age of onset are less likely to experience choreography. Chlorate will be more present in people with an early age between 15 and 18 years old. People with older adolescent HDs are more likely to experience adult HD-like symptoms. Approximately 25-30% of people with initial HD experience recurrent seizures, an uncommon symptom in adults. 

The diagnosis of Huntington's disease is usually based on the results of neurological, psychological, and genetic testing. Neurological examinations are conducted by a neurologist who intensively interviews individuals to obtain medical records and other conditions. Testing of neurological and physical functions can review reflexes, balance, movement, muscle tone, hearing, walking and mental status. The primary use of doctors in diagnosing HD is to take a family history called pedigree or genealogy. It is very important to be honest and truthful to a family member. This is because other family members may not be diagnosed correctly for this disease, but there may be other problems. Genetic testing is the most effective and accurate HD testing method, a direct genetic test that uses the DNA extracted from a blood sample to calculate the number of CAG repeats of the HD gene. HD diagnostics are supported if there are more than 36 iterations. Less than 26 repetitive test results block HD. Some individuals repeat at the borderline range. For such individuals, doctors can try to get a clearer picture of disease risk by asking other family members to come in for consultation and genetic testing. The last method is Diagnostic imaging. In some cases, physicians may recommend brain imaging, such as computed tomography (CT) or more likely magnetic resonance imaging (MRI), especially if a person's family history and genetic testing fail to reach a conclusion. As the disease progresses, these scans typically reveal contraction of striations and cortices and enlargement of cavities filled with fluids called ventricles in the brain. However, this change does not necessarily mean HD because it can occur in other disabilities. Conversely, a person can have early symptoms of HD and still have normal findings on CT scans or MRI scans. 

Many medications can be prescribed to control the emotional and movement problems associated with HD. However, although drugs can help suppress these clinical symptoms, there is no cure to stop or reverse disease progression. Most medications available for HD symptoms are effective by modulating the neurotransmitter, a chemical message that travels back and forth between neurons. In many of these drugs, the mechanism of action for HD is not fully understood. Tetrabenazine, which causes the depletion of the neurotransmitter dopamine, is prescribed to treat involuntary movements associated with Huntington, such as di-terterevenazine. Other drugs, such as risperidone, olanzapine, haloperidol, and other drugs such as clonazepam can help relieve uncomfortable movements and can be used to suppress hallucinations, delusions, and intense explosions. However, antipsychotic drugs do not typically help with muscle contraction associated with dystonia, and they can actually aggravate the condition, causing rigidity and rigidity. In the case of depression, doctor may prescribe citalopram, fluoxetine, sertraline, bortexeline or other compounds. Tranquilizers can help control anxiety, and lithium can be prescribed to cope with morbid excitement and serious emotional changes. 

In Hong Kong, between 1984 and 1991, the penetration rate of HD was 3.7 per million inhabitants. Since the ancestors of these families with HD can be linked to coastal areas with a strong history of colonial rule, it has been proposed that these examples have European origins. HD is rare, especially in Japan, with 1-4 patients per million population, roughly one tenth of the population of most European and European populations. It has been hypothesized that HD mutations in Japan have a distinct origin from HD mutations in Europe and Africa. 

Europe has a relatively high penetration rate of HD, which is 40 to 100 per 1 million people. Fashion is uniform in almost every region of Europe except Finland. Studies in the UK have shown that HD is high and relatively uniform throughout the country, and there is no clear correlation with race. In 1981, a study in South Wales found that 761 HD patients per million were prevalent. A study conducted in the Grampian area of ​​NW Scotland in 1989 found that 99.4 per million HD infections were abnormally high. In Northern Ireland, a 1994 study found 64 cases of HD infection per 1 million people.

In conclusion, Huntington's disease has a unique sequence in the Huntington gene located on chromosome 4p16.3, in which three bases of CAG are repeated. Huntington's disease is a disease in which the sequence of CAG repeats is abnormally increased, and it is the three major symptoms of dementia, mental symptoms and dementia. In the early stages of disease, ballooning is relatively localized to the body, but as the disease progresses, ballooning spreads throughout the body. It takes 15 to 20 years from diagnosis to death. The Huntington gene located on chromosome 4p16.3 has a sequence in which three bases of CAG are repeated, and Huntington's disease is caused by an abnormally increased sequence of this repeating sequence. The average number of CAG repetitions is about 19 times for normal people, but more than 40 times for Huntington disease patients. The repetition frequency is inversely proportional to the age at onset of Huntington's disease. There is currently no cure for Huntington's disease. However, researchers have tried many ways to slow down defective genes. This includes stopping the production of toxic proteins through DNA and RNA-based approaches. Most recently, researchers have also begun working with the CRISPR / Cas9 system, one of the most promising genetic editing tools to date. CRISPR / Cas9 systems are much easier, faster and more specific than past tools. Researchers cannot predict how long this experiment will take, but they expect to be able to treat Hunting's disease through the above methods.


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16 December 2021
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