Paternity testing intentionally falsified
People sometimes doubt about the accuracy of DNA paternity tests, and these doubts are centered on the likelihood of sharing genetic markers with other people. However, the procedure of taking the sample is often overlooked although it is a much more likely source of problems. A case reported by a DNA lab from the University of Granada, Spain reminds us about the importance of proper sampling, and at the same time shows that a DNA test can not easily fooled.
The case, published in The Journal of Forensic Sciences by investigators from the Department of Legal Medicine seemed to be a routine DNA paternity test at first, but the results showed a very atypical profile, inconsistent with either inclusion or exclusion of the alleged father from paternity. Instead, the genetic profile from the alleged father showed a number of peaks higher than expected. in addition, an anomalously strong signal was evident for the amelogenin locus, a genetic marker located on chromosome X. The lab tests where repeated taking extra caution. A different technician was assigned, and a completely different set of reagents and controls was employed. However, the results stayed the same. After a careful reanalysis, the investigators came to the conclusion that the sample carried DNA from a second individual, probably a woman. Considering the evidence, they suspected that the alleged father had intentionally contaminated the sample to obtain a false conclusion about his relationship with the child.
Finally, when the alleged father was summoned to the lab and presented with the evidence and the investigators’ hypothesis, he admitted having put in his mouth saliva from another person before having the DNA sample taken with a buccal swab. The purpose for this was to be excluded as the father of the child. Although not frequently, attempts to adulterate DNA samples to produce a false paternity statement use to happen, and a closer monitoring of the DNA sampling procedures is critical, especially in cases with legal implications.
