Role of 'Junk' DNA

Treasures in the Trash
Matthew Herper Robert Langreth, 12.12.05
What genetic researchers used to call junk DNA may conceal the most
important medical secrets of all.

When researchers began mapping the genome, aiming to decode the entire
human gene sequence, they expected to eventually locate 100,000 or more
active genes. After completing the genome map in 2001, they were
startled to find that humans have only 25,000 active genes. The lowly
roundworm has almost as many (19,000).

That means the active genes contain a mere 1.5% of the 3 billion units
of DNAthat make up our genetic structure. The rest is "dark" or "junk"
DNA, long presumed to be present for no particular reason.

But researchers are now finding this junk DNA, overlooked for decades
by geneticists, may actually not be junk at all. They are finding hints
of an enormous and previously unimagined command-and-control apparatus
that regulates what our 25,000 genes do and how the body is assembled.
Junk DNA, when it goes wrong, may be a culprit in major killers ranging
from cancer to diabetes to infectious disease.

That insight could unearth hundreds of new targets for experimental
drugs that had been aimed only at working genes. "It's sort of like
Antiques Roadshow," says Harvard genome scientist John Quackenbush, who
has long argued that the junk DNA could be vital. "You look in the
closet full of junk and find out you have a Picasso."

"This will revolutionize human genetics over the next few decades,"
says David Haussler, a Howard Hughes investigator at UC, Santa Cruz who
was on the government team that decoded the human genome. He predicts
that most disease-causing genetic flaws will be found lurking in our
junk DNA.

The dark DNA "may be even more important" than active genes in causing
disease, says Isaac Bentwich, chairman of Israel's Rosetta Genomics.
Founded in 2000, Rosetta has applied for patents on 200 dark genes. He
hopes for new treatments and diagnostic tools for lung cancer, prostate
cancer and other diseases.

More at:
http://www.forbes.com/forbes/2005/1212/092_print.html

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