Though it has been suggested that the frequency of HD is probably low among people of African origin, documentation remains poor and evidence is inconclusive. From the few known cases, however, it has been hypothesized that the HD mutation in Africa has a separate origin from the mutation in Europe or Japan.
There is a substantial frequency of HD in the white and mixed-race populations of South Africa. Most of the families with HD have Dutch or British ancestry, which suggests that they inherited the European HD allele. A 1987 study revealed the HD prevalence among South African blacks to be very low – around 0.6 cases per million people.
Huntington’s disease is believed to have first arrived in South Africa over 300 years ago when Dutch colonists settled into the Western Cape in the 1600’s. Dr. Michael Hayden, a South African researcher, traced back the origins of the disease in this country and noted the following in his groundbreaking research released in the 1980’s:
“Among the 344 persons who arrived on the Dordrecht at the Cape in 1658 was a man called Willem Schalkv.d. Merwe. His family had its origins in Oud-Beyerland, which is in the vicinity of Rotterdam. On 5 May 1661, he became one of the first free burghers at the Cape and in 1668 he married Elsjie Cloeten, daughter of lacob Cloeten who arrived at the Cape with lan van Riebeeck in 1652. The first child of this marriage was a daughter named Sophia after her maternal grandmother. She married Roelof Pasman on 12 November 1684 and they had 5 children before he died in 1695. In 1696 she married Pieter Robberts, who was to become one of the first magistrates in the Cape, and after 1699 they lived on a farm, Rustenburg, in the Stellenbosch district. A search through old manuscripts and documents revealed a map of the Cape of Good Hope, drawn between 1699 and 1713 by a cartographer named Valentyn, in which farms and the names of owners are marked. Over 50 smaller affected families, who link up to form 4 very large Afrikaner families, have been traced over 14 generations to these common ancestors.
Three of these are descendants of the marriage between Sophia v.d. Merwe and Roelof Pasman and the other large affected kindred stems from the later marriage of Sophia to Pieter Robberts.”
Hayden’s research highlights the relatively high prevalence of HD in those of Afrikaner descent and other European ancestry within South Africa. (There is current research in the works to determine the prevalence of other ethnicities within the region.) Hayden’s other research paper, The Prevalence of Huntington’s Disease in South Africa, was a groundbreaking study in the 1980’s, as it was the first attempt to document the prevalence of Huntington’s disease in South Africa. At the time, Hayden used ethnographic studies of the Western Cape to estimate that there were 22 per million in coloured and white populations and 0.1 per million in Black South Africans affected by the disease (Click here for more information). It is important to note that these figures were minimum estimates of prevalence and that much of the research focused on families in the Western Cape where the Dutch settlers first arrived. Further research is in the process of determining more accurate prevalence for the Coloured and Black populations of South Africa.
Furthermore, research from Baine et al. (2013) highlights differences in the HD gene itself, with black patients experiencing more occurrence on haplogroup B (a haplogroup is a genetic population that shares a common ancestor), versus haplogroup A for white and coloured populations in South Africa. The average number of CAG repeats in unaffected black Africans is significantly lower than the mean CAG in white South Africans. However, there have been no studies yet to investigate the reason for this within the black population.
Research is greatly needed across the world to determine current disease prevalence, in addition to research on the genetics of Huntington’s disease in black African communities. These numbers are incredibly important for lobbying government and other funders in order to convince them to allocate resources to affected populations.
Huntington’s Association of South Africa
The Huntington’s Association of South Africa’s (HASA) mission is to “assist families with Huntington’s Disease by providing knowledge and support through support groups, creating awareness about HD through fund-raising and providing financial assistance where possible.” HASA manages support groups in Cape Town and Gauteng and provides many other support services.
For more information, visit http://www.huntingtons.org.za/
Dr. Michael Hayden
Michael Hayden is the world’s most cited author on Huntington’s disease. In the 1980’s, Dr. Hayden led a study of the prevalence of Huntington’s disease in South Africa. Dr. Hayden then moved to Canada and continued to focus on Huntington’s disease research. His lab became the first to successfully cure a mouse of the disease. Currently, he is the Chief Scientific Officer of Teva Pharmaceuticals and continues to advocate for Huntington’s disease research through his work there.
Jessica Selfe is one of the directors of the Huntington’s Association of South Africa (HASA), an organized started in 2004 to better serve the HD population of South Africa. Selfe is gene-positive, but not yet symptomatic. As a result of this awareness and having HD in her family, Selfe is improving access to care through her intense advocacy and devotion, leading to the development of several support groups in Cape Town, Pretoria and Johannesburg. She was also one of the individuals responsible for the hiring of the first social worker for HD families in the country.
Lysle Turner, a South African from the Gauteng province, is a mountaineer and fitness guru who is using his international fame to shine a spotlight on Huntington’s disease. After one of his family members was diagnosed with the disease, Turner decided to use his celebrity status and climb mountains in order to use the publicity to raise money for organizations like the Huntington’s Association of South Africa. In early 2015, Turner attempted to become the first person to scale Everest in honor of Huntington’s disease families, but a major avalanche that closed the mountain halted his efforts. Turner hopes to continue his efforts to raise awareness for HD through his passion for sports.
For Further Reading^
1. Baine, Fiona K., et al. “Huntington disease in the South African population occurs on diverse and ethnically distinct genetic haplotypes.” European Journal of Human Genetics 21.10 (2013): 1120-1127.
2. Hayden, M. R., et al. “The origin of Huntington’s chorea in the Afrikaner population of South Africa.” S Afr Med J 58.5 (1980): 197-200.