User talk:Z3389806

History

Huntington's disease has existed since at least the seventeenth century and several physicians provided earlier descriptions of hereditary chorea but without much detail. In 1872, Huntington’s disease was first documented with great details by George Huntington in “On Chorea”.(link) Huntington’s disease was initially known as chorea, derived from the Greek word “khoreia” which means dancing in unison. (link: http://www.memidex.com/choreography+notational-system#etymology). George Huntington described the disease as “an heirloom from generations away back in the dim past” as he realized that HD was hereditary. This conclusion was reached when he observed that if one of the parents had the disease, the offspring will inevitably have the disease too. In his paper, “On Chorea”, he described:

"Of its hereditary nature. When either or both the parents have shown manifestations of the disease ..., one or more of the offspring almost invariably suffer from the disease ... But if by any chance these children go through life without it, the thread is broken and the grandchildren and great-grandchildren of the original shakers may rest assured that they are free from the disease.".

Huntington thus was able to explain the precise pattern of inheritance of autosomal dominant disease years before the rediscovery by scientists of Mendelian inheritance.

Epidemiology

There seem to be an increased prevalence of Huntington's disease among Europeans as compared to Africans and Asians. European populations exhibit a comparatively high prevalence with 4-8 per 100,000 individuals suffering from HD. Two of the most well-known populations in which high prevalence of HD was notably in the state of Zulia, Venezuela and Northern Ireland. The overall prevalence of HD in Mexico was also expected to be comparable or even higher to that of European populations..

Country/Region	Prevalence of HD (individuals per 100,000)
Tasmania	12.1
Northern Ireland	6.4
South East Wales (UK)	6.2
Olmsted County, Minnesota (US)	6 - 6.6 (1960) & 1.8 - 2 (1990)
Valencia Region (Spain)	5.38
Slovenia	5.16
Oxford Region (UK)	4.0
New South Wales (Australia)	0.65
Japan	0.65
Finland	0.5
Taiwan	0.42
Hong Kong	0.37

Table 1 Prevalence of Huntington's Disease in various parts of the world

Table 1 shows the prevalence of HD in different parts of the world, with regions ranked according to how prevalent HD is. Countries with the highest prevalence are from Europe with most appearing at the top of the table whereas Asian countries are found at the bottom half of this table. This indicates the lower prevalence of HD in Asia as compared to that in European populations. This observation is further supported by a study done by Shiwach and Lindenbaum (1990), it was found that the minimum prevalence of HD among immigrants from the Indian subcontinent was found to be almost half that found in the indigenous UK population. For those areas where there are intermarriages with Europeans, there is a higher occurrence of the disease. This is related to the higher frequency of huntingtin alleles with 28–35 CAG repeats in Europeans and the fact the disease is autosomal dominant.

In a paper by Warby et al. (2011), it was reported that HTT haplotypes contribute to the difference in prevalence of HD between European and East Asian populations. Haplotypes are sets of single-nucleotide polymorphisms (SNPs) on a single chromosome of a chromosome pair that are statistically associated. Different HD haplotypes have different mutation rates, resulting in expansion of CAG tract (marker for HD). Hence, for HTT haplotypes with higher mutation risk such as A1 and A2 halotypes, individuals are more susceptible to HD due to CAG expansion and this corresponds to higher prevalence. This is supported by the findings that higher risk A1 and A2 HD halotypes composed the majority of HD chromosomes in Europe whereas it is absent in China and Japan.

HD Halotypes	General Population	HD Chromosomes
Tasmania	12.1
Northern Ireland	6.4
South East Wales (UK)	6.2
Olmsted County, Minnesota (US)	6 - 6.6 (1960) & 1.8 - 2 (1990)
Valencia Region (Spain)	5.38

Table 2 PHTT haplotype frequency in East Asia and Europe

The incidence rate of HD increases with age. It was reported in Taiwan that the range of age at which most onset of HD occurs is between 40-49 years in males and between 50-59 years in females. This trend is similar to that reflected in a Northern Ireland study, whereby the age group in which the highest number of HD onset occurs is 40-44 years. Both of the above-mentioned studies concluded that there is no significant difference for the age of onset between males and females, indicating no sexual predominance for HD.

Treatment

There is no cure for Huntington's disease. Similar to AIDS, only the symptoms can be treated to slow down the progression of the disease.

Medications

• Movement disorders
• Psychiatric disorders

Therapies

• Psychotherapy
• Speech Therapy
• Physical Therapy
• Occupational Therapy

Quite recently, there are a couple of breakthroughs for the treatment of Huntington's.

• Five siRNAs targeting three SNPs may provide therapy for three-quarters of Huntington's disease patients.
• Using adult neurotrophic factor-secreting stem cells.

<a href="http://www.disabled-world.com/health/neurology/breakthrough-cure.php">Huntington's Disease Breakthrough May Provide Cure</a>