Massive encyclopedia helps explain how the human genome works

By Carolyn Y. Johnson, Globe Staff

A massive consortium of researchers, led in part by local scientists, has taken the next step after researchers mapped the human genome, compiling an encyclopedia that illuminates how the vast majority of the 3 billion building blocks of human DNA works.

When the genome, the blueprint of a person, was first deciphered 11 years ago, scientists were faced with a conundrum: only a tiny fraction was made up of genes, the stretches that carried instructions to make proteins that gave rise to inherited traits, such as having blue eyes or black hair. The rest was called junk DNA.

The raft of publications being released in top scientific journals Wednesday should permanently change the meaning of junk. Hundreds of scientists from 30 institutions elucidated the functions of 80 percent of the genome, finding regulatory elements that act like switches, determining which genes are on or turning their volume up or down.

The information, gained through more than 1,600 experiments on cells from 147 types of tissue could help explain the causes of human disease, because many studies that scan the genome for changes associated with common illnesses such as diabetes or cardiovascular disease have highlighted areas that have no genes, but may be important in regulating genes.

This is Google Maps, said Eric Lander, director of the Broad Institute, a genomic research center in Cambridge that participated in the new project, called ENCODE for Encyclopedia of DNA Elements. The human genome project gave us the picture of the whole human genome like a satellite image, but its not immediately obvious: where are the cities, where are the pizzerias, where are the coffee shops, where are the highways, what has traffic.

The new data, he said, give scientists the ability to understand how the genome works and begin to unravel human disease.

The effort does not have a single, simple finding, but provides a resource that will be useful in making sense of genetic information. It also helps solve a puzzle that first emerged when the human genome was sequenced: why so few genes?

When the genome was published, people had all kinds of speculations about how many genes there are in the human genome -- the number thrown around was 100,000 genes, said Zhiping Weng, director of the program in bioinformatics and integrative biology at the University of Massachusetts Medical School, who will play a leading role in the next phase of the project. When it became clear it was 25 to 30,000 genes, a lot of people are very upset, and why? Because the fly has 20,000 genes, the worm has 20,0000 genes, and are we just bigger? What exactly makes us us? Its how our genes are regulated.

Weng will lead a four-year, $8 million grant to continue the analysis and integration of the vast amounts of information as scientists continue to understand the function of the remainder of the genome and apply the techniques developed to understand the genome more broadly.

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Massive encyclopedia helps explain how the human genome works