The National Institute of Standards and Technology (NIST) has developed a new technique for analyzing DNA. With this method, samples that were once considered too damaged or degraded to be analyzed through conventional methods can now be accurately identified.

The procedure was most recently used to positively identify the remains of 16 additional victims of the Sept. 11 attacks on the World Trade Center. Only one of several other advanced analysis tech-niques being used in the WTC identifica-tion effort, the new method requires a smaller DNA sample size for positive identification.

Conventional procedures that use “short tandem repeats” (STRs) analyze DNA fragments from 13 specific locations within the human genome. Each fragment carries approximately 200 to 400 pairs of the nitrogen-containing compounds (“base pairs”) that comprise an individual’s genetic code.

The NIST approach still uses fragments from designated locations, but they are smaller and involve 25 to 190 fewer base pairs. The smaller sample size means DNA samples that are damaged or degraded are still likely to contain intact sections at each location.

This research was funded by the National Institute of Justice and will be explained in an issue of the Journal of Forensic Science.

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