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Biology and Genetics of New Autosomal STR Loci Useful for Forensic DNA Analysis



John Butler, Becky Steffen


Short tandem repeats (STRs) are accordion-like regions of the human genome that vary in length (through expansion or contraction) with a core repeated DNA sequence. Forensic laboratories commonly use tetranucleotide repeats, containing a four base pair repeat structure such as GATA. In 1997, the FBI Laboratory selected 13 STR loci that form the backbone of the U.S. national DNA database. Building on the European expansion in 2009, the FBI announced plans in April 2011 to expand the U.S. core loci to as many as 20 STRs to enable more global DNA sharing. Commercial STR kits enable consistency in marker use and allele nomenclature between laboratories and help improve quality control. The STRBase website, maintained by the U.S. National Institute of Standards and Technology, contains helpful information on STR markers used in human identity testing.
Forensic Science Review


short tandem repeat, STR, DNA typing, autosomal genetic markers, core loci, 13 CODIS STRs, European Standard Set, STR kits, forensic DNA, DNA


Butler, J. and Steffen, B. (2012), Biology and Genetics of New Autosomal STR Loci Useful for Forensic DNA Analysis, Forensic Science Review (Accessed April 15, 2024)
Created January 4, 2012, Updated March 26, 2024