Human Genome Work Reaches Milestone

Article excerpt

It's official. Biology's hottest race has been declared an amicable tie, even though one competitor has a clear lead and neither has actually reached the finish line or knows exactly what the prize contains.

In an accomplishment being compared to landing a man on the moon, rival groups of scientists from the private and public sectors announced on June 23 that each has read essentially all of the 3 billion or so letters that spell out the human genome, the genetic information encoded within the 6 feet of DNA coiled up in every human cell.

"Today, we celebrate the revelation of the first draft of the human book of life," said Francis Collins of the National Human Genome Research Institute in Bethesda, Md., at a White House celebration.

The announcement, considered premature by some scientists, nevertheless drew praise from leading biologists and government officials worldwide. Calling the reading of the genome "a stunning and humbling achievement," President Clinton stressed its medical implications.

"With this profound new knowledge, humankind is on the verge of gaining immense new power to heal. Genome science will have a real impact on all of our lives--and even more, on the lives of our children. It will revolutionize the diagnosis, prevention, and treatment of most, if not all, human disease," he said.

While scientists celebrated the genome announcement, some of them appealed for stronger federal legislation to protect people from genetic discrimination by their health insurance companies or employers. The unveiling of the human DNA sequence should offer a "wake-up call," demonstrating that we can't delay addressing this issue any longer, says Collins.

The world received its initial look at deoxyribonucleic acid, better known as DNA, more than a century ago. In 1869, German scientist Friedrich Miescher isolated a novel chemical, now known to be DNA, from immune cells left in the pus on bloody bandages.

It took nearly a century for scientists to recognize DNA as the hereditary material of plants, animals, and microbes and determine that its molecular shape is a double helix reminiscent of a spiral staircase. The two sides of the helix consist of complementary strings of so-called bases, which come in four forms that geneticists abbreviate A, C, T, and G. One base joins with a partner on the opposite strand--A with T, or G with C--to create the steps on DNA's staircase.

The sequences of bases within a gene encode the information that a cell uses to build a protein. In the late 1980s, several scientists raised the provocative idea of sequencing all human genes as well as the even greater lengths of DNA in between--whose functions were, and still are, largely unknown.

"There were people who thought this was sheer lunacy," recalls Collins.

This week's announcement emerged from an uneasy truce forged between Celera Genomics, a biotech firm in Rockville, Md., and the Human Genome Project, a publicly funded, international consortium of scientists now led by Collins. The latter group, formed in 1990, had the task of sequencing the human genome largely to itself until 1998. Then, geneticist J. Craig Venter brashly predicted that his new company, Celera, would do the same job in less time and for less money (SN: 5/23/98, p. 334).

The competing camps took different approaches. The public effort, funded in large part by two U.S. agencies--the National Institutes of Health and the Department of Energy--and Wellcome Trust, a British charity, first broke the genome into manageable chunks of DNA. The group then mapped the order of these pieces, called clones, with respect to each other. Only in the past few years have Collins and his colleagues focused on sequencing those clones.

In Venter's more radical strategy, previously used to read the genes of many bacteria and the fruit fly, Celera shattered human DNA into snippets whose ends were immediately sequenced. …