Usefulness of genetic sequencing questioned

Some experts say more study of anatomy is needed instead

others hold out hope for cures

Science

September 09, 2005|By Dennis O'Brien | Dennis O'Brien,Sun Staff

The list reads like a Who's Who of the animals that keep us company or help us earn a living: the dog, the cat, the chicken, the horse, the cow, the mouse, the rat, the rabbit and the elephant.

At great public expense, all have had their genomes sequenced -- their DNA has been sliced and diced into genetic building blocks to help scientists discover more about humans and the ailments that trouble them.

But when researchers announced the latest addition to the genome list last week, it made national headlines, thanks to the nature of the beast -- our closest living relative, the chimpanzee. The $25 million chimp project was part of a federal program to sequence animal genomes that costs taxpayers $130 million a year.

Some enthusiasts claimed that data from the project proved Darwin's theory of evolution beyond a reasonable doubt. Others said the information could eventually make it easier to develop treatments for diseases such as Alzheimer's and Parkinson's.

But some scientists are now questioning whether the expensive and complex sequencing of so many animal genomes is worth the effort. They argue that science needs more research on the anatomy and physiology of the animals themselves -- and less into genetic heritage.

"We've sequenced all these animals, but it really doesn't help much yet because we don't know the functions of so many human genes, or their counterpart genes in other animals," said Bernard Wood, an anthropology professor and an expert on apes and evolution at George Washington University.

"You could say that the technology has advanced beyond our ability to make good use of the information."

Wood's review of the anatomical differences between chimpanzees and humans, published a few years ago in Proceedings of the National Academy of Sciences, found that of 1,700 anatomical structures in humans, there are only 200 counterpart structures that match up in chimps.

"We still don't know enough about chimpanzees," he said.

Genome sequencing is the process of identifying the order of the billions of pairs of genetic code that dictate an organism's functions and characteristics. To sequence a genome, researchers extract DNA from a blood or tissue sample and use sophisticated machines to identify the arrangements of the long chains of chemicals, known as "base pairs," that together form different genes.

But the genetic code is written in an unfamiliar language, so sequencing a genome of any plant or animal doesn't immediately lay open its genetic secrets.

"Until we know at least something about the function of every gene, we're still working with a hand over one eye," said Richard Gibbs, director of the Human Genome Sequencing Center at the Baylor College of Medicine in Houston.

As a scientific spectator sport, genetic sequencing has been grabbing headlines since June 26, 2000, when researchers gathered at the White House to announce the sequencing of the human genome. They promoted the achievement as a major breakthrough that would open doors to the curing of diseases.

But the fanfare may have raised too many hopes about quick fixes for intractable diseases. Nothing in science ever comes that easily, skeptics note.

"What was wrong was our own expectation. We were overly enthusiastic in thinking we would get a lot of bang for our buck, too quickly," said Akhilesh Pandey, a molecular biologist and biochemist at the Johns Hopkins School of Medicine.

Marc D. Hauser, a chimpanzee expert at Harvard, says that more money should go into researching chimpanzees in their habitat to solve mysteries about their lifestyles and capabilities. "We've sequenced the genome of the chimpanzee, but there's still a lot of questions about the chimpanzees themselves, particularly in the wild," he said.

But Dr. Francis S. Collins, director of the National Human Genome Research Institute, says that in the long run, the animal genome sequencing will be worth it.

"It's the single most powerful tool we have for understanding what we're made of and what's different about us," said Collins. "It is a phenomenally powerful tool."

Collins and others say that sequencing animals is important because it enables researchers to compare animal genomes with comparable genes in humans. In the process, we can pinpoint causes and cures for diseases, he said.

"Almost everything we've learned about the human genome has come from our ability to study the genomes of other organisms. The human sequence without the comparisons would be vastly less useful. Without them, we'd still be staring at the human genome, wondering what it all means," Collins said.

It was by comparing the chimp and human genomes, for instance, that researchers found six regions in the human genome that show the strongest signals for natural selection -- the process by which organisms winnow out harmful traits and reward beneficial ones. It's in these regions that researchers are most likely to find genes that control human-specific abilities, such as language.

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