Are DNA Test Infallible?

Abstract

Modern technology has strongly influenced most fields of knowledge and forensic sciences do not escape this reality. With the advent of the application of molecular biology to human identification by means of DNA typing, conceptual conflicts were introduced. After over 15 years of worldwide experience, the robustness and reliability of DNA analysis was demonstrated. However in Latin America, judges, prosecutors and defenders, due in part to different educational background as compared to scientists, may ignore potential restrictions concerning DNA profiling results. Since its beginnings, DNA testing was surrounded by an aura of infallibility. Nowadays, a big number of highly polymorphic genetic markers, included in commercial kits, as well as automated devices for DNA extraction and purification, PCR amplification, electrophoresis and data analysis are available. Nevertheless, errors may occur. This work describes the main causes for errors in DNA testing in forensic laboratories that simultaneously processes hundreds or thousands of samples a month and makes suggestions to prevent each particular problem. It is important to underscore that DNA testing should be considered one more piece of evidence within the context of a criminal or forensic investigation, and that the judicial sentences should be based on the evidence as a whole and not just on the genetic studies.