To determine the genetic profile, tandem repetitive sequences (STR) are used. These sequences, also called microsatellites, are a class of genetic markers consisting of tandem sequence repeats with a size of two to seven base pairs. The alleles of STR locus change according to the number of repeats of the given sequence motive. Due to high level of polymorphism (informativity) and Mendelian inheritance, the microsattelites became suitable genetic markers for the study of diversity, parentage tests and the genetic identity.
STR alleles are determined by means of multiplex polymerase chain reaction (multiplex PCR). One of the primers of each pair is at 5´-end labelled with a fluorescent dye. Fragments are divided and detected in only one electrophoretic probe using an automatic electrophoresis device.