Humans show major DNA differences

A UK-led team made a detailed analysis of the DNA found in 270 people and identified vast stretches in their codes to be duplicated or even missing. A great many of these variations are in areas of the genome that would not damage our health, Stephen Scherer and colleagues told the journal Nature. But others are - and can be shown to play a role in a number of disorders. To date, the investigation of the human genome has tended to focus on very small changes in DNA that can have deleterious effects - at the scale of just one or a few bases, or "letters", in the biochemical code that programs cellular activity. And for many years, scientists have also been able to look through microscopes to see very large-scale abnormalities that arise when whole DNA bundles, or chromosomes, are truncated or duplicated. But it is only recently that researchers have developed the molecular "tools" to focus on medium-scale variations of the code - at the scale of thousands of DNA letters. Big factor This analysis of so-called copy number variation (CNV) has now revealed some startling results. It would seem the assumption that the DNA of any two humans is 99.9% similar in content and identity no longer holds. "http://news.bbc.co.uk/2/hi/science/nature/6174510.stm":[ http://news.bbc.co.uk/2/hi/science/nature/6174510.stm]

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