Introduction: Huntington's disease was first described by American doctor George Huntington in 1872, while his grandfather also noticed this disorder, that's why this disease is known as Huntington's.
This disease is the most common monogenic neurodegenerative disease in the Western world, which is a brain disorder that is caused by mutations in the Huntingtin gene and is transmitted in an autosomal dominant manner. and as a result of multiple repetitions of cytosine, adenine and guanine (CAG) in the coding region of the gene located in the short arm of chromosome 4.
Before the discovery of the HD gene, it was pointed out that the age of onset of HD is related to the gender of the affected parents, but with the discovery of that gene, it was found that the earlier the age of onset, the higher the number of triple repeats for a given patient. In people with this disease, the number of CAG repeats, the age of onset of the disease, and the severity of the symptoms are different. For the normal HTT gene, which is a wild type gene, there can be between 6 and 26 of these repetitions, and more than 26 repetitions lead to problems. People who have 27 to 35 repetitions are unlikely. get HD, but they can transmit this disease to the next generation. People with 36 repetitions or more of HD and more than 40 repetitions have full penetrance of the disease. This disease also has a juvenile form that is expressed with more than 60 repetitions.
Methods: All the information obtained about Huntington's genetic disease was done through searching terms such as disease diagnosis method, symptoms, treatment, prevalence and mortality statistics in Google Scholar's reliable scientific database from 12019 to 2023, and in the end, a general summary of 21 valid scientific review and research articles was made. And a series of important and significant information was collected and included in this article.
Results: According to the research conducted, the prevalence of the disease worldwide is widely different between men and women, and Western populations such as Canada, the United States, England, and Australia have the highest prevalence.
While African and Asian countries such as Japan, Korea, Thailand and Hong Kong have a lower prevalence of the disease; In general, this disease is estimated between 4 and 10 cases per 100,000.
The disease may begin at any age and may be asymptomatic for years. Its occurrence is usually in the middle-aged period of the late 3rd or early 4th decade, but 6% may occur under the age of 20. The symptoms of HD are in three areas: motor, cognitive and psychiatric, where behavioral disorders and symptoms usually precede motor characteristics, and depression is the most common. .
Other symptoms are endocrine disorders, homeostasis changes, immune changes that increase cytokines, and psychiatric symptoms are involuntary choreic movements. In the movement symptoms, it is abnormal in two ways, involuntary or voluntary, which causes problems in walking.
HD disease can be diagnosed through clinical symptoms and genetic testing, but it is difficult to determine when a person has changed from an asymptomatic carrier to a diseased state.
Conclusion: Current treatments are mostly limited to treating symptoms because there are no treatments to prevent the onset or slow the progression. Tetrabenazine is the only drug approved for the treatment of the disease in North America and some European countries, however, it can increase depression as a potential side effect. In Europe, antipsychotic drugs are often used.
In the last decade, there has been a great growth in potential therapeutic targets and clinical trials, and due to the monogenic nature of the disease, they are seeking to inhibit the expression of the HTT gene, so that they can directly target the primary disease mechanism.