Katrina's Next Challenge: Identifying the Dead

DNA matching will be put to the test, but time is an enemy

THURSDAY, Sept. 15, 2005 (HealthDay News) -- As coroners continue to gather the dead across the Gulf Coast, the nation's DNA labs are gearing up for months -- even years -- of tedious efforts to identify hundreds of bodies.

In just the four years since the 9/11 terror attacks, scientists have polished their abilities to extract DNA from human remains, and they now have sophisticated computer programs in place to help handle number-crunching.

But the aftermath of Hurricane Katrina poses unprecedented challenges.

With DNA-bearing personal property like hairbrushes and toothbrushes washed away, identification will become more complicated and less precise. And a trio of threats -- heat, humidity and time -- may keep some identities hidden forever.

All three forces can kill off the sturdiest DNA -- the longer a body is away from refrigeration, the faster it decays.

"The degradation of the remains will be a challenge in the coming weeks and is a large factor in the success of the DNA work to come," said Kevin McElfresh, executive director of the Bode Technology Group, a DNA analysis laboratory, in Springfield, Va.

No one knows how many bodies will be discovered in the states -- notably Louisiana, Mississippi and Alabama -- battered by the hurricane. The official death toll is currently 710 -- including 423 in Louisiana, mostly in New Orleans -- and is expected to rise as recovery efforts continue.

When bodies are unidentified, coroner teams will try to extract DNA, in many cases from bones. It's also possible to take DNA from blood, but that's not feasible when bodies are badly decomposed.

Laboratories will then try to extract DNA from body samples. Typically, they'll look for data from 13 locations in the DNA that together provide a "unique bar code" -- a DNA fingerprint -- for each person, McElfresh said.

In both the 9/11 and last year's tsunami identification efforts, investigators often asked for the personal effects of the dead to isolate DNA from, say, hair on a brush. Then they could match it to DNA from a dead person.

After the World Trade Center attacks, scientists examined more than 20,000 individual body parts, said Bob Shaler, a forensic biologist who oversaw the New York City identification efforts. The bodies of more than half of the nearly 2,800 victims were ultimately identified. But the effort isn't over -- some recovered, unidentified remains are still in storage, awaiting advances in testing technology, he said.

In some cases, 9/11 investigators had to turn to relatives of victims to find genetic links and identify bodies. But unlike the Manhattan attacks, when many of the victims' families lived in the New York area, relatives of hurricane victims are now scattered across the country, Shaler said, making it challenging to get samples.

"What you hope is that both a mother and father, or multiple children and a wife or husband are available so that the entire bar code of the remains can be accounted for," McElfresh said.

Both fathers and mothers pass DNA -- deoxyribonucleic acid, which carries an individual's genetic information in cells -- to their children. If, for example, a father is missing in the aftermath of Hurricane Katrina, a laboratory could extrapolate the "bar code" of his DNA by analyzing his children's DNA and ignoring the genetic contribution of the mother, McElfresh said. Armed with that data, investigators could then compare the bar code to the DNA of human remains.

Laboratories can also look at mitochondrial DNA, which is passed from mothers to their children. Since it's passed through the maternal line, it would link a grandmother to her daughter's child, or a man to a cousin on her mother's side, since they share the same grandmother, McElfresh said.

But mitochondrial DNA won't link a father to his children. In that case, investigators must turn to the DNA of the male Y chromosome, which is passed from fathers to sons and could link, say, an uncle to his nephew.

Y-chromosome testing has taken off in the past few years. One of the pioneers in its use is a company called ReliaGene, which literally found itself at the center of the storm. It's based in New Orleans, and its headquarters survived the hurricane.

Now its employees, who are safe and sound, await the chance to help identify the bodies of fellow Crescent City residents.

More information

Learn more about forensic DNA from the Human Genome Project.

SOURCES: Kevin McElfresh, Ph.D., executive director, Bode Technology Group, Springfield, Va.; Bob Shaler, Ph.D., forensic biologist, New York City
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