Useless DNA found to resist deletion

U.S. researchers say they have discovered DNA that has no known function is much less likely than other DNA to be lost during evolution.

Stanford University Assistant Professor Gill Bejerano and graduate student Cory McLean studied small segments of DNA called "ultraconserved" regions that can be deleted with no effects on the animal's health or functioning. They discovered the ultraconserved regions are 300 times less likely than other regions on the gene to disappear during mammalian evolution.

"The true function of these regions remains a mystery," said Bejerano, adding that the fact they are so highly conserved means "it's clear that the genome really does need and use them."

Bejerano first identified the ultraconserved regions in 2004, and found that some regions help regulate the expression of neighboring genes. Other research, however, demonstrated that mice missing all or some of the regions appear perfectly normal. That finding is usually interpreted to mean the absence of any important functional role for the missing segments of DNA. But the researchers say the extreme conservation of the regions, however, suggests they have a highly important role.

The study appears in the journal Genome Research.