An Oxford University statistician has helped to dispel doubts about a study that identified Icelanders as a uniquely pure gene pool suitable for ground-breaking medical research.
Peter Donnelly is a member of a four-strong team engaged in a war of words over whether Icelanders are the descendants of British women carried off by Vikings to settle and populate an outlying territory, or the children of a more diverse group of people.
At stake is the lucrative genetic database comprising the medical records of Iceland's entire population. The country's tiny isolated population makes it an obvious choice for genetic study. First settled in 900AD by around 10,000 people, the island's population stayed below 50,000 until 1850. Today, it is just 280,000.
In 2000, Agnar Helgason, who works for private genetics research company deCODE, published a paper in the Annals of Human Genetics , suggesting the majority of Icelanders were descended from a small number of British females and Norwegian men. His claim was based on analysis of mitochondrial DNA, passed directly through the female line, and the Y-chromosome, passed through the male line.
Einar Árnason, professor of evolutionary biology and population genetics at Iceland University, disputed the claim, responding with a paper exposing the data used by Dr Helgason as flawed. He said it had come from German and Danish databases known to be riddled with copying errors and had led the deCODE team to make false conclusions.
Professor Árnason is also a member of Mannvernd, the Association of Icelanders for Ethics in Science and Medicine, an organisation formed after the Icelandic government passed a law in 1998 allowing the population's medical records to be handed to deCODE, which then entered the data into a genetic database, a move opposed by Mannvernd. Anyone who objected to inclusion had to opt out.
Professor Árnason argues that Iceland's population was no more genetically homogeneous than that of other European countries. "There's nothing special about Iceland," he told The THES .
But Dr Helgason has hit back with new data sets analysed by Professor Donnelly, which, he says, prove conclusively that Icelandic people have one of the least diverse gene pools in Europe, along with the Orkney Islanders and Ashkenazi Jews.
He suggested his rival was trying to undermine the work of deCODE. "The problem is that different statistics give you different aspects of diversity. What he is measuring is the diversity of the European gene pool.
It's quite clear that Iceland is among the most homogeneous populations in Europe."
Professor grnason is still not satisfied, saying his rival's choice of comparator countries was skewed to push Iceland further up the league of genetic homogeneity. He plans to publish another paper, to further argue that Iceland has a particularly diverse gene pool.
The extent of diversity could be crucial in the hunt for genes that are linked to disease. Having fewer genes to analyse would make it simpler to identify mutations that cause disease.
But Professor Donnelly said the debate was academic. "There are lots of other reasons why Iceland may be a good place to look for genes: good genealogical records, good medical information, people willing to participate. DeCODE has proved one of the most successful groups internationally in mapping these disease genes."