Two More Human Genomes Mapped

WEDNESDAY Nov. 5, 2008 -- Scientists report that they've mapped the third and fourth genomes of individuals, an Asian man and an African man, providing insight into the genetic makeup of different races.

The analysis of the DNA of the two men suggests that the much-hyped days of individualized medical care designed for each person's genetic makeup is close at hand, said Dr. James R. Lupski, a leading genetics specialist.

"We're getting a little glimpse of what will happen over the next couple of years," said Lupski, vice chair of the Department of Molecular and Human Genetics at Baylor College of Medicine. Genetic analysis will give scientists more insight "from an evolution standpoint, from a disease standpoint," he said, while providing "a basic understanding of what makes us different as persons."

Until now, scientists have only mapped the individual genomes of Nobel laureate James Watson, co-discoverer of the DNA double helix, and genomics pioneer Craig Venter.

Scientists believe that all humans are more than 99 percent identical. The remaining tiny fraction of genes make each person distinct and can help explain individual differences in susceptibility to disease and physical responses to the world.

Both studies, which are in the Nov. 6 issue of Nature, are collaborations of scientists from around the world.

One looked at the genetic blueprint of a man from Ibadan, Nigeria, a member of the Yoruba ethnic group. The other maps the genome of a man from the Han Chinese ethnic group.

The men aren't identified.

The new research is unique, because it shows that scientists are getting a better handle on detecting errors in the genome, Lupski said.

Using the metaphor of the genome as a book and letters as genetic coding, Lupski said that in the past, scientists could figure out that single letters in words had been changed. Now, they can notice if "a sentence is missing or two words are inverted, or the typesetter has duplicated a sentence."

Lupski added that he's impressed that the genetic research didn't take long. "Each time [new research] comes out, it's faster and cheaper," he said.

It won't be long before it costs just $10,000 or $20,000 to sequence a person's genetic makeup, he predicted, "and then it's only a matter of time until we get to the $1,000 genome."

Earlier this year, researchers announced plans to map the genomes of 1,000 people from around the world. The goal is to use more sophisticated technology to understand genetic blueprints on an even deeper level.

But scientists still need to figure out how the data they're gathering from the human genome translates into medical advances, said Charles Lee, director of cytogenetics at the Harvard Cancer Center.

"We are at a stage where technology is outpacing our biological understanding," he said. "We have massive amounts of genetic information being generated, but a limited understanding of what this data means to the individual. There is still a long way to go before we can accurately interpret much of the data that we are generating."

More information

Learn more about human genetics from the Oak Ridge National Laboratory.

Posted: November 2008


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