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



John M. Butler, Carolyn R. Steffen


Short tandem repeats (STRs) are regions of tandemly repeated DNA segments found throughout the human genome that vary in length (through insertion, deletion, or mutation) 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 data 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.
Topics in Forensic DNA Analysis: Current Practices and Emerging Technologies
Publisher Info
CRC Press (Taylor & Francis), New York City, NY


forensic science, DNA, forensic DNA, short tandem repeat, STR, STRBase


Butler, J. and Steffen, C. (2013), Biology and Genetics of New Autosomal STR Loci Useful for Forensic DNA Analysis, CRC Press (Taylor & Francis), New York City, NY, [online], (Accessed May 22, 2024)


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Created August 18, 2013, Updated June 24, 2021