Tiny signposts to major cures

An analysis of the genetic differences between three racial groups has provided scientists with one of the greatest potential insights into the nature of some of the most intractable illnesses of the modern era, from heart disease to mental disorders.

Researchers have itemised the smallest possible variations in the DNA of 71 individuals from European, African and Chinese origins in order to unravel the role of genes in diseases that are common to all of humanity.

It is the first detailed map of some of the key "genetic signposts" in three groups of people from different ethnic backgrounds. The signposts will ultimately point scientists in the direction of finding the causes and treatments for some of the most common illnesses, including diabetes and cancer.

Such maps will also help doctors to prescribe more effective drugs that are targeted at an individual's genetic makeup, as well as helping to understand why some people are more prone to certain illnesses than other individuals.

David Hinds of Perlegen Sciences, a biotechnology company based in Mountain View California, who led the research team, said: "We've created the first detailed map of common genetic variation in humans."

But he warned that the pioneering research should not be used to justify racial classifications because any genetic differences that they had detected between ethnic groups were relatively minor.

Dr Hinds told the American Association for the Advancement of Science in Washington DC that the data would be useful for starting to address such questions as which kinds of medical treatments should be used, based on physiological differences caused by genetic variations.

The Perlegen scientists, who published their findings in the journal Science, concentrated on identifying the smallest possible mutations that distinguished each of the 71 individuals in the study. They mapped 1.58 million of these "single nucleotide polymorphisms" (SNPs) on each person's set of chromosomes.

Scientists believe that the reason why some people respond well to certain drugs, while others do not, is largely due to differences in these SNPs - or "snips" as scientists call them. Equally, snips may account for why some people get heart disease or cancer early in life whereas others who may have a less healthy lifestyle, live healthier for longer.

Most of the 1.58 million snips were common to all three ethnic groups. For instance, 94 per cent of the snips were found in both of their variants in the African Americans in the study, 81 per cent were in both variants in the European Americans and 74 per cent in the Chinese American group.

The company, which is collaborating with publicly funded research institutes in America working on the same problem, found that 7 million of the most common snip mutations occurred within just 5 per cent of the entire human population. Another 4 million snip mutations are less common, turning up in between 1 and 5 per cent of the world's entire population.

- INDEPENDENT