Dealing with Degraded DNA: A Cautionary Tale

DNA technologies have become a standard part of forensics investigations.  DNA analysis can tell you all about the person it came from.  DNA analysis can also help identify an unknown person who cannot otherwise be identified.

But what happens when the DNA has been degraded?  The person may have been the victim of fire, drowning or another cataclysmic event that damaged the remains.

Technologies can help here as well.  PCR (polymerase chain reaction) can replicate a single copy of a DNA strand, allowing it to be amplified by several orders of magnitude.  Real-time PCR (also known as quantitative or qPCR) even allows the replication process to be monitored in real-time, while it is occurring.

A forensic case reported by the state of Victoria, Australia, highlights the benefits – and limitations – of working with degraded DNA.

Human remains were located in a national park.  Investigators hoped to connect them to a known missing person case.  nDNA (nuclear DNA) profiling showed a match to the mother of the missing person.

However, mtDNA (mitochondrial DNA) profiling showed some inconsistencies.

As a result, additional nDNA profiling was done with the father of the missing person.  More inconsistencies were found.  Despite the initial nDNA match with the mother, investigators concluded that the remains were not from the missing person in question.

The Victorian Institute of Forensic Medicine utilized a DNA 1000 chip on an Agilent Bioanalyzer system to visualize the PCR amplification of the DNA samples.

In conclusion, the investigators emphasize “the importance of using more than one type of DNA analysis.”  In addition, the case study stresses “the importance of having a multidisciplinary approach to investigate whether a missing person case and unidentified human remains are one and the same.”

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