In forensic work, DNA from a biological sample and from a known reference material (most often, buccal swabs or blood) are amplified by multiplex PCR with fluorescence-labeled primers and separated by CGE. As a result, unique DNA profiles are generated from both the evidence and the known reference sample and compared to determine whether the patterns are similar.
If the DNA profiles match, then the suspect cannot be excluded as a source of the questioned sample. Likewise, if the DNA profiles do not match, the suspect can be excluded as the donor of the questioned sample. The analysis of 6–10 STRs provides a random match probability of approx 1 in 5 billion.
DNA typing is a useful tool in crime solving, not only for blood samples, sperm, or saliva but also for traces of DNA left on tools or pieces of clothing used in burglaries or thefts. On these kinds of samples, the sources of DNA are extremely small amounts of skin debris left after gripping tools. When a sensitive technique such as PCR coupled with CGE is used, it is possible to get a profile from these low amounts of DNA.
CE provides efficient separation, resolution, sensitivity, and precision for a reliable genotyping of STR loci. Sizing precision of <0.16 nucleotide standard deviation is obtained with this system, thus allowing the accurate genotyping of variants that differ in length by a single nucleotide.
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