A new technique that uses a simple cotton swab sample to accurately confirm relatedness between two individuals as distant as second cousins has been developed by the researchers at Kyoto University.
With more DNA datasets at hand, the method, described in the journal PLOS ONE, could be utilised to identify disaster victims in mass floods and tornadoes that destroy entire communities.
"Up till now, the accuracy of verifying pairwise blood relations between parents and children were 95 percent and siblings around 72 percent. With slightly more distant relatives like aunts and uncles it goes down to five percent. As for cousins and second cousins, it was practically impossible," said one of the study authors Keiji Tamaki.
The researchers explained that all it takes for the new method to work is a dab inside the cheek with a cotton swab. From these samples it is possible to compare 170 thousand single nucleotide polymorphisms (SNP), which are locations where the genetic code varies minutely from person to person.
Instead of simply comparing how each individual SNP matches, they examined how many consecutive matches there were to confirm relatedness between distant relatives.
"This approach greatly improves pairwise kinship analysis of distant relationships, specifically in cases involving identification of disaster victims or missing persons," the study said.
"Our inspiration for the project came from tsunami victims in the 2011 Great East Japan earthquake," lead researcher Chie Morimoto said.
"Many tsunami victims passed away, and over 70 of them have yet to be identified even though five years have passed," Morimoto noted.
For the time being the team only has enough information for the Japanese population, but with sufficient data the researchers believe that the method could be applied anywhere in the world.