Thursday, October 28, 2010

Scientists Map 95% Of Human Gene Variations

An international team of scientists has mapped 95 per cent of the genetic variation that can occur in any human, completing the first phase of the 1000 Genomes Project, which aims to produce a comprehensive public resource to help researchers study all types of genetic variation that might cause disease in humans.

The map, and an account of how the consortium behind the project compiled it, appears in a paper published in the 28 October issue of the journal Nature.

Many of the variants had been identified already, but more than half are new: so far 95 per cent of the currently measurable variants in any person have been found, and when completed, the project will have identified more than 99 per cent of all human variants.

The new map also includes some surprises.

For instance, the researchers found that on average, each of us has between 250 and 300 genetic changes that would cause a gene to stop working properly, confirming that none of us has a "perfect" genome. Another surprise was that each person carries between 50 and 100 genetic variations that have already been linked with an inherited disease.

However, because we each carry two copies of a gene, one from each biological parent, the chances are that we stay healthy, as long as one of the copies is ok.

As well as looking at common variants, the researchers looked in detail at the genomes of two families of three members each: mother, father and daughter.

They located new variants in the daughters that were not present in either of their parents. This helped them determine the rate of mutation of DNA in humans, which they worked out to be about 60 new mutations per generation (ie variants that are not passed on from the parents, but are still "faults" compared to the "perfect" genome).

The work was spread across three pilot studies where the researchers used next-generation DNA sequencing technologies to map genetic variation in 180 people.

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