Hereditary hemochromatosis is a deadly but treatable disease which is found predominantly in individuals of European descent. The gene mutation most commonly associated with hemochromatosis is C282Y. Almost 85 to 90% of all individuals who are clinically affected with hemochromatosis test positive for the C282Y gene mutation, and studies have shown that in non-clinically diagnosed individuals, 10 to 33% of individuals who test positive for 2 copies of the C282Y mutation eventually go on to experience the morbidity associated with hereditary hemochromatosis.
The strong genetic association of this disease with the C282Y mutation, and the striking prevalence of this mutation in individuals of European ancestry has led researchers to investigate the history of C282Y, including the location in Europe where it first originated and how this mutation eventually spread throughout Europe. To tackle this study, scientists have conducted large scale screenings for the C282Y mutation in various indigenous populations throughout Europe in an effort to pinpoint the population distribution pattern of C282Y and retrace its mode of spread.
To follow is a table summarizing the distribution frequencies of C282Y in indigenous populations in various regions of Europe:
Table 1. Population Frequency of C282Y mutation in various regions of Europe
|Country #||individuals screened||C282Y allele frequency|
|Sweden (Sami People)||151||2.0|
|UK (N.E. England)||117||7.7|
|UK (Jersey Islands)||411||8.3|
|UK (Orkney Islands)||103||4.9|
The population studies conducted to date show a very interesting and distinct distribution pattern for the C282Y marker in Europe. The highest frequencies of this mutation are found along the coastline of Europe. Furthermore, the frequency of C282Y is highest in Western Europe and declines significantly moving east. Also, the frequency is highest in Northern Europe and declines significantly moving south.
DNA studies have also shown that the C282Y mutation likely first arose in Europe approximately 60 to 70 generations ago. Assuming that each generation is 20 to 25 years, that would place the origin of this mutation to approximately 1200 to 1750 years ago, with subsequent rapid spread along the coastline of Europe and disseminating from Northern and Western Europe. The timing and pattern of spread of this mutation has a very close correlation to the migration of Vikings and locations of Viking settlements in Europe beginning around the same time, resulting in the “Viking hypothesis" for the C282Y marker which suggests that the C282Y mutation is associated with Vikings.
Further studies to investigate the “Viking Hypothesis" found that C282Y is found in greatest frequencies in regions that are known to be Viking settlements. For example C282Y is found in high frequencies in the Scandinavian countries including Iceland and the Faeoroe Island, which are known to be colonized by Vikings. Further support of the Viking Hypothesis was indicated by studies which showed that the lowest frequencies of C282Y were found in regions of Europe that were not affected by Vikings such as Central Europe, the Balkans, the Mediterranean countries and Russia.
The genetic studies to date suggest that the C282Y mutation first arose in Europe and was spread by Vikings and later by the Normans throughout Europe, indicating a genetic link between hereditary hemochromatosis and Viking ancestry. Moving forward, ongoing studies in the research community will focus on forensic DNA testing of Viking skeletons to obtain definitive proof of the origins of the C282Y mutations and solidifying a Viking link to this prominent European genetic disease.
Olsson, K., Konar, J., Dufva, I., Ricksten, A., Raha-Chowdhury, R.. (2010). Was the C282Y mutation an Irish Gaelic mutation that the Vikings helped disseminate? HLA haplotype observations of hemochromatosis from the west coast of Sweden. European Journal of Haematology, 86, 75-82.
Milman, N., and Pedersen, P.. (2003). Evidence that the Cys282Tyr mutation of the HFE gene originated from a population in Southern Scandinavia and spread with the Vikings. Clinical Genetics, 64, 36-47.