Short tandem repeat
is a molecular biology
method used to compare specific loci
from two or more samples. A short tandem repeat
is a microsatellite
, consisting of a unit of two to thirteen nucleotides repeated hundreds of times in a row on the DNA strand. STR analysis measures the exact number of repeating units. This method differs from restriction fragment length polymorphism analysis
(RFLP) since STR analysis does not cut the DNA with restriction enzymes. Instead, probes are attached to desired regions on the DNA, and a polymerase chain reaction
(PCR) is employed to discover the lengths of the short tandem repeats.
STR analysis is a tool in forensic analysis
that evaluates specific STR regions found on nuclear DNA
. The variable (polymorphic) nature of the STR regions that are analyzed for forensic testing intensifies the discrimination between one DNA profile and another. Forensic science takes advantage of the population's variability in STR lengths, enabling scientists to distinguish one DNA sample from another. For example, the likelihood that any two individuals (except identical twins) will have the same 13-loci DNA profile can be as high as 1 in 1 billion or greater.
<!--The Federal Bureau of Investigation (FBI) has chosen 13 specific STR loci to serve as the standard for CODIS. The purpose of establishing a core set of STR loci is to ensure that all forensic laboratories can establish uniform DNA... Read More