One man’s trash, another man’s treasure: Scientists discover “junk” DNA has uses

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Published time: September 06, 2012 21:32
Edited time: September 07, 2012 01:32

For decades more than 98 percent of our genetic code was dismissively labeled “junk” DNA. But a massive new study shows that it actually plays a crucial role – a discovery that could revolutionize science and medicine.

We know that only 1.2 per cent of our genetic code contains specific instructions for how to synthesize proteins that create the cells that make us who we are.

As for the rest? It was assumed to be useless baggage, or at the very least, its function wasn’t obvious.

In 2003 a $120 million project called Encode was launched to find out what, if anything, is happening in the rest of the DNA. It united more than 400 scientists in over 30 labs all around the world.

The results were published in 30 different scientific papers this week, and have blown up our understanding of the gene.

The rest of the DNA may be regulatory elements, or using a simple metaphor, switches.

"Regulatory elements are the things that turn genes on and off," says Professor Mike Snyder of Stanford University, a principal investigator in Encode "Much of the difference between people is due to the differences in the efficiency of these regulatory elements. There are more variants, we think, in the regulatory elements than in the genes themselves."

“I don’t think anyone predicted that would be the case,” says Dr. Bradley Bernstein, an Encode researcher at Massachusetts General Hospital.

Encode claims that 80 percent of all DNA seems to have some biological function.

"These parts of the DNA have important implications for the growth and development of embryos and foetuses during pregnancy. These are the kinds of elements that make your tissues and organs grow properly, at the right time and place, and containing the right kinds of cells," says Anne Ferguson-Smith of Cambridge University.

They also regulate the predisposition towards illnesses like cancer, diabetes and Crohn’s disease.

Tim Hubbard of the Wellcome Trust Sanger Institute in Cambridge gives an example: "We know that breast cancer is not one disease but there's multiple types of breast cancer with all sorts of different mechanistic processes going wrong.”

"A given drug only works in about a third of the people you give it to, but you don't know which third. A lot of that is related to genomics, so if you knew the relationship between a person's genome and which drugs work for them and which ones they shouldn't take because it gives them side effects, that would improve medicine."

But the geneticists say they do not yet know what “switch” corresponds to what “instruction”, and gene-targeted medicines could still be decades away.

"This is not the 100 metres, we are not Usain Bolt. This is much more a marathon where we have to emulate Mo Farah," sums up Ewan Birney, chief analysis co-coordinator of Encode.