Scientists: 80% of human genome plays indispensable role

About 80 percent of the entire human genome, the blueprint of the human body, plays an indispensable role in maintaining life, scientists have found.

The results of joint international studies by an Encyclopedia of DNA Elements (ENCODE) project, published Sept. 6 in Nature magazine, show that large parts of the genome previously believed to be meaningless in fact have their own important functions, including gene regulation.

These findings have the potential to change humankind's understanding of genetics and could be useful in developing new drugs.

The human genome refers to the complete set of DNA, which forms the basis of chromosomes in human cells. It was announced in 2003 that the entire human genome had been decoded.

But genes, which are the blueprint of proteins that make up the human body, account for only about 2 percent of it. While investigation of mutations in genes can help predict the likelihood of some diseases, scientists had yet to understand the functions of the remaining 98 percent of the genome.

Detailed research by the ENCODE project, of which Japan's Riken national research institute is part, found that 80.4 percent of the human genome functions as switches that instruct genes to generate proteins, necessary to maintain life, at required locations and timings.

The failure of those switches to function properly may trigger diseases, and links with cancer and dementia have already been established.

"Some diseases, such as diabetes and hypertension, cannot be explained by a single genetic mutation," said Ituro Inoue, a professor of human genetics at Japan's National Institute of Genetics. "In such cases, genome analysis sometimes turns up obvious differences in domains that have been thought meaningless. These latest results may help clarify the mechanisms of those diseases."

Thirty-two research institutions from Japan, the United States, Britain, Spain and Singapore have participated in the ENCODE project, which started in 2003. Its latest results will be published in 30 research articles.