Life Script by Nicholas Wade

Author:Nicholas Wade
Language: eng
Format: epub
Publisher: Simon & Schuster
Published: 2001-07-15T00:00:00+00:00

One of the most interesting searches for disease genes is a wonderfully inventive experiment designed by K·ri Stef·nsson. An Icelandic neurologist, Stef·nsson conceived the idea that the special properties of Iceland’s people and history made the population particularly suitable for tracking down the genetic roots of complex diseases. Icelanders are descended from a small number of founders, probably 8,000 to 20,000 people, who discovered and settled the islands between A.D. 870 and 930. Some 75 percent of the men were probably Vikings from Scandinavia and the Viking settlements in Britain. 13 Most of the women were Gaelic, brought as wives and slaves from Britain. The women seem also to have included people from many other parts of Europe, so the founding population was probably not particularly homogeneous, 14 despite Stef·nsson’s initial belief that Iceland possessed “unique genetic homogeneity.” Still, the genetic diversity was probably substantially reduced by three disasters that befell the population: an outbreak of pneumonic plague in 1402–4 that carried off 45 percent of Iceland’s inhabitants; a 35 percent reduction in 1708 caused by smallpox; and a 20 percent reduction in 1784–85 because of the famine that followed a volcanic eruption.

Because few if any new settlers arrived after the founding in the tenth century, most Icelanders can trace their lineages back to a founding ancestor. The country has extensive health care records of every major illness going back to 1915 and centralized autopsy samples that date back for half a century. All these features make the Icelanders excellent subjects on which to try to trace the pedigrees of complex diseases. The reason is that disease-causing gene variants are much easier to identify if everyone in a population inherited the variant from the same ancestor. There is a good chance that they also inherited stretches of DNA on either side of the gene along with their markers—the geneticists’word for any recognizable piece of DNA such as a SNP. If apparently unrelated people with schizophrenia, say, have a particular pattern of SNPs, the SNPs may well lie close to a gene variant that contributes to the disease. In larger populations, the particular gene variant may be surrounded by a variety of different SNPs, making it much harder to locate.

Stef·nsson formed deCODE Genetics in 1996 as a “ populationbased genome company,” with the idea of running a national health database for the Icelandic government and at the same time looking for disease related genes. In return, the government granted the company exclusive rights to market the database abroad for twelve years. 15 The idea was of such interest to the Swiss pharmaceutical firm Hoffmann–La Roche that in 1998 it paid more than $200 million for the rights to any genes deCODE might discover to be involved in such diseases as schizophrenia, heart disease, Alzheimer’s, and emphysema.

The scheme drew criticism both in Iceland and abroad, chiefly on the ground that it would be impossible to protect the privacy of the Icelanders whose health records were being mined. In December 1998, after a

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