STR Typing and Available Multiplex Kits Including Validation Methods

Since the first introduction of DNA typing in 1987, more than 30 years have been passed and an enormous growth in forensics occurred. DNA test routinely represents the most important tool for solving forensic caseworks and biological relationships. Forensic laboratories carry out annually hundreds of DNA tests because modern technologies allow obtaining conclusive results from a wide range of biological evidences even if degraded or in small quantities. Repeated DNA regions selected by the international scientific community for forensic applications include minisatellites (VNTR) and microsatellites (STR). In particular STRs became rapidly the first-choice markers for human identification because of their features and the good polymorphism degree. Once loci were definitively established, commercial multiplex were developed including initially only few loci till to current large systems that allow now simultaneous amplification of European and USA database core loci. Thus nowadays, large commercial STR kits are widely used either in forensic than in paternity tests because of their easy use and high discriminatory power. Obviously, to assess new forensic DNA technologies, two types of validation are required: developmental performed directly by the manufacturer and internal done by the user—laboratory. According to the Scientific Working Group on DNA Analysis Methods (SWGDAM) recommendations, several different steps are required in both cases.