The identity of a cell line can be determined by analysing a number of highly polymorphic loci - Short Tandem Repeat (STR) loci - dispersed throughout the genome.
STR profiling is a well-established technique that unambiguously characterises a number of different loci in the human genome and provides a reference standard for human cell lines.
Thus, it is the method recommended by The American Type Culture Collection (ATCC) for cell line authentication .
Likewise, STR-profiling is well established in DNA-based forensics and paternity testing.
STR loci consist of short, repetitive sequence elements 3–7 base pairs in length. These repeats are well distributed throughout the human genome and are a rich source of highly polymorphic markers, which can be detected using PCR. Alleles of STR loci are differentiated by the number of copies of the repeat sequence contained within the amplified region and are distinguished from one another using fluorescence detection, following electrophoretic separation.
 American Type Culture Collection Standards Development Organization Workgroup ASN-0002.