Genetics breakthrough: How 'junk DNA' is actually useful

Sep 6, 2012

Huge team of scientists find DNA thought to be useless could revolutionise the treatment of diseases

AN INTERNATIONAL team of researchers has made a significant breakthrough in understanding how the human genome works. The Encode project, a scientific collaboration involving researchers from more than 30 countries, has revealed that large swathes of the human genome previously thought to be useless, and termed 'junk DNA', in fact play a crucial role in regulating the manufacture of proteins in the body. The discovery could revolutionise the understanding and treatment of hundreds of diseases.

Junk DNA is the part of the genome that does not contain any genes. Genes are important because they direct the body to make specific proteins, which in turn are the building blocks of our cells and bodies. When the human genome was decoded a decade ago, there seemed to be surprisingly few of these genes in our make-up: just over 20,000. (Most scientists had expected around 100,000.)
That represents around two per cent of our total complement of DNA. The rest was simply labelled 'junk DNA' and was assumed to have accumulated by accident during the evolution of our species. But now the Encode project has shown that much of this junk DNA actually plays a key role inside the human body.

The Encode scientists have found that large stretches of junk DNA play an active role by regulating those 20,000-odd genes and controlling how they make proteins.

Using new technology not available to the original Human Genome Project, the researchers discovered that this junk DNA acts as a genetic control panel with 'switches' for our main genes, slowing down and speeding up the way they make proteins.

Ewan Birney, who spearheaded the collaboration from the EMBL-European Bioinformatics Institute near Cambridge, told the Independent that junk DNA, far from being useless, was "absolutely full of life - of things doing stuff".

The Encode project represents a significant advance in our understanding of how the human genome really works and the results have the potential to transform the way we treat disease.

For example, some of the switches the researchers discovered in the junk DNA have already been linked to illnesses such as Crohn's disease, diabetes and heart conditions. Many of these ailments have a genetic component but until now researchers had focused on looking for errors linked with the genes themselves. The Encode findings show the fault may lie elsewhere in our DNA, in our so-called junk DNA.

Ian Dunham, of the European Bioinformatics Institute, told the Financial Times: "Encode data can be used by any disease researchers, whatever pathology they may be interested in. In many causes you may have a good idea of which genes are involved in your disease but you may not know which switches are involved."

However direct applications stemming from Encode's work will not be instant. Brad Bernstein of Harvard University, an Encode investigator, said: "We now have a map of the genomic locations of these switches, but we don't have a map showing which switch controls which gene. "What turns on the switch? And when it turns on, what gene or genes [are affected]? Having a map of the way these elements are wired and connected is a critical goal."

  • The results of the five-year Encode project were published yesterday across 30 papers in the journals Nature, Science, Genome Biology and Genome Research.

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