A millennium ago, a group settled in Iceland and have stayed there ever since, with few people coming and going. And so their DNA has stayed remarkably homogenous. That's a major boon for genetics researchers, who today have released the results of sequencing the complete genomes of 2636 Icelanders — the largest such countrywide project ever.
Researchers at Decode Genetics, an Icelandic company owned by Amgen, have sifted through the complete DNA sequences of 2636 people huntings for mutations that cause disease. This is a massive undertaking, but one made easier by the low level of genetic diversity in Iceland. With fewer genetic variants to sift through, it's easier to find meaningful variants.
Think of it as a smaller haystack in which to look for needles.
The results are published today in four papers in Nature Genetics. The researchers, who also had access to the medical histories of the participants, were able to identify several new mutations linked to disease. For example, notes Carl Zimmer reporting for the New York Times, a mutation in MYL4 caused early onset of a particular type of irregular heartbeat. And there's more:
The scientists also found a rare mutation to a gene called ABDB4 that raises the risk of gallstones. And they identified a gene called ABCA7 as a risk factor for Alzheimer's disease. Previous studies had suggested a gene in the genetic neighbourhood of ABCA7 was associated with the disease. But the Icelandic study pinpointed the gene itself — and even the specific mutation involved.
The study also identified "human knockouts", or people who have a nonfunctional copy of a particular gene. Scientists are especially interested in studying these people to figure out how a nonfunctional gene affects them. There's still, hopefully, many more insights to come from the this volcanic island in the north. [New York Times, Nature Genetics]