Gene study and rearranged DNA

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Gene study sheds new light on human differences

Thu Sep 27, 2:48 PM ET

US researchers have discovered that individual differences in humans may have more to do with rearranged chunks of DNA, rather than specific gene mutations, suggested a study published Thursday.

The findings, which showed as many as 1,300 structural variations between two women of different ethnic descent, could shed light on new ways to combat disease, said researchers at Yale University.

"The focus for identifying genetic differences has traditionally been on point mutations or SNPs -- changes in single bases in individual genes," said Snyder, senior author of the study published in Science Express.

"Our study shows that a considerably greater amount of variation between individuals is due to rearrangement of big chunks of DNA."

Researchers used a new method of study DNA called paired-end mapping in order to examine structural variants between one female of African descent and one of European descent.

The approach involved breaking up the "genome DNA into manageable-sized pieces about 3,000 bases long," after which point scientists "tagged and rescued the paired ends of the fragments, and then analyzed their sequence with a high-throughput, rapid-sequencing method developed by 454 Life Sciences," the study said.

"Previous work, based on point mutations estimated that there is a 0.1 percent difference between individuals, while this work points to a level of variation between two- and five-times higher," Snyder said.

"We also found 'hot spots' -- particular regions where there is a lot of variation," said first author of the study Jan Korbel, a researcher at Yale.

"While these regions may be still actively undergoing evolution, they are often regions associated with genetic disorder and disease."

The authors said that scientists may have to alter their approach when examining gene variation in the hunt for disease because components of the human genome "may be more variable, and possibly more flexible, than previously thought."

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