DNA Analysis Aids Efforts to Identify New York Disaster Victims

Bijal P. Trivedi
for National Geographic Today
September 19, 2001
The destruction of the World Trade Center has led to the largest and
most gruesome forensics project in history.

Rescue teams are
working around the clock retrieving body parts from the rubble for
DNA analysis. The combined impact of the plane crashes, fuel
explosions, and collapse of the two towers burned and tore many
bodies beyond recognition, so DNA analysis is the only way to
identify the victims. No intact bodies have been found and there is
little hope now that any exist.

As of two o'clock Wednesday afternoon, 109 people had been identified. But the number changes minute to minute, said Ellen Borakove, a spokeswoman for the New York City medical examiner's office.

The 109 identifications made so far were based on conventional methods such as fingerprints, unique scars, jewelry, and dental records.

As rescue workers discover human remains, all body parts are collected and sent to the medical examiners office, where each sample is logged.

Authorities in the office would not comment on how many samples have been received. Borakove did say, however, that Associated Press reports stating that "body parts are coming in 400 a day now, and the medical examiner's office is bracing for one million in all" are incorrect. Estimating the total number of body fragments likely to be recovered is impossible, she said, adding that "every sample will be tested."

Creating "Genetic Fingerprints"

Because the workers cannot determine whether various body parts are from the same victims, all the tissue found is being collected for testing.

It's also important to collect the samples so that once the victims have been identified, the remains can be returned to their families for last rites.

The New York City medical examiner's office has recruited two genetics companies—Celera Genomics of Rockville, Maryland, and Myriad Genetics of Salt Lake City, Utah—to assist with DNA analysis.

Celera, known for its role in sequencing the human genome, and Myriad, which has played a major role in developing genetic tests to determine susceptibility to breast cancer, both have facilities for high-volume genetic testing.

Myriad Genetics will create a "genetic fingerprint" of each sample based on 13 regions, or loci, of the human genome that in combination present a unique profile.

Matching DNA Samples

Once cells are damaged, the DNA contained within them begins to disintegrate. The more heavily damaged samples with degraded chromosomal DNA will be analyzed by Celera, which can create a genetic profile based on another kind of DNA (mitochondrial) also found in the cells.

Meanwhile, relatives are proving medical examiner's office with personal items that may contain DNA samples of the possible victims. The New York City medical examiner's office will analyze these DNA samples to compile a "genetic fingerprint" that can be compared with the tissue from the site.

Relatives and friends have been pouring into a Family Assistance Center in Manhattan to deliver a variety of items that were used exclusively by the missing persons: combs, brushes, toothbrushes, razors, undergarments, eating utensils, cigarette butts, and chewing gum.

Some estimates have suggested that rescue workers won't finish combing through the debris until at least early next year. It's not known how long the tissue could be useful for genetic testing, although cold weather would help preserve the tissue and its DNA.

In a statement, New York City Mayor Rudy Giuliani said: "DNA evidence offers us the best opportunity to help families find their loved ones. I strongly urge everyone who is missing a relative to participate in this process."

© 1996-2008 National Geographic Society. All rights reserved.