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Molecular Pathology

Polymerase Chain Reaction

Current applications

 

Author: Rodney E. Shackelford, DO, Ph.D. (see Authors page)

Revised: 22 September 2012, last major update January 2010

Copyright: (c) 2008-2010, PathologyOutlines.com, Inc.

 

Note: As PCR applications are voluminous, references are meant to be illustrative, and not complete

 

Archeology and evolution

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● DNA that has survived in ancient tissue up to 45,000 years old can be amplified to provide large quantities for sequencing

● Analysis of DNA from ancient organisms is used to study ancient species, as well as evolution (Genome Res 1991;1:107)

 

DNA sequencing

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● Determining the order of DNA bases

● The traditional Sanger method is not based on PCR, but some newer sequencing methods use PCR to make copies of the DNA before the sequencing begins (Wikipedia)

● Although PCR introduces replication errors, DNA sequencing of the total PCR product may give the correct sequence because (a) errors occur in only a small percentage of the bases, (b) the incorporation of incorrect bases is essentially random, (c) new DNA polymerases have lower frequencies of mutations due to proofreading capabilities (Human Molecular Genetics 2; Garland Science 1999, Chapter 6)

 

Forensic identification

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● To identify individuals, forensic scientists scan 13 DNA regions, or loci, that vary from person to person, and use the data to create a DNA profile of that individual (“DNA fingerprint”)

● Information is stored in the CODIS database, funded by US FBI (Wikipedia)

● There is an extremely small chance that another person has the same DNA profile for a particular set of 13 regions (US Department of Energy, Human Genome Project Information)

● PCR is used to make millions of exact copies of DNA from a biological sample, which allows use of biological samples as small as a few skin cells

● Note: great care must be taken to prevent contamination with other biological materials during the identifying, collecting and preserving of a sample

 

Medical and pathogen diagnosis

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● Hemoglobinopathies (Clin Lab Haematol 2004;26:159)

● Measuring residual disease post-treatment (Clin Lymphoma Myeloma 2009;9 Suppl 3:S266)

● Prenatal diagnosis of aneuploidy (Folia Histochem Cytobiol 2007;45 Suppl 1:S11)

● Diagnosis of specific infectious disorders, including Aspergillosis / fungi (Rev Iberoam Micol 2007;24:89); BK virus (Clin J Am Soc Nephrol 2006;1:374) or other viruses (Curr Issues Mol Biol 2007;9:87); Salmonella / bacteria (J Infect Dev Ctries 2008;2:421); Schistosomiasis / parasites (Mem Inst Oswaldo Cruz 2006;101 Suppl 1:145)

 

Molecular genetics

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● Study of the structure and function of genes at the molecular level

● Includes study of how genes are transferred from generation to generation (Wikipedia)

 

Molecular pathology

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● Identification of gene rearrangements associated with specific tumor types (Jpn J Clin Oncol 2007;37:79)

● Molecular classification of leukemia (Br J Cancer 2007;96:535)

 

Paternity testing

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● Use of genetic fingerprinting to determine if a man is the biological father of an individual

● Current techniques use PCR and restriction fragment length polymorphisms

● Older techniques used ABO blood group typing, analysis of other proteins or HLA antigens

● In a DNA parentage test, the probability of parentage is 0% if the alleged parent is not biologically related to the child, and typically > 99.9% if the alleged parent is biologically related to the child (Wikipedia)

 

Tissue identification

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● PCR is part of a process of tissue fingerprinting to identify specimen mix-up, cross contamination, floaters or carry-over artifacts (Adv Anat Pathol 2008;15:211, J Mol Diagn 2007;9:205, Am J Clin Pathol 1993;100:666)

 

Transplant engraftment analysis

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● Transplant engraftment studies are used to evaluate the level of donor versus recipient cells in post-transplant specimens

● Unique DNA fingerprints from recipient and donor are used to determine the proportion of each contained within the total DNA extracted from the post-transplant specimen; these percentages correspond to relative amounts of donor and recipient cells in the specimen

● Engraftment studies are sequentially performed on transplant patients to monitor closely the levels of donor and recipient cells so that appropriate therapeutic intervention can proceed, if necessary

● Analysis often uses short tandem repeats (STRs) as part of the “fingerprint” (Bone Marrow Transplant 2002;29:243)

 

Tumorigenesis

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● PCR helps understand the importance of particular molecules and pathways that may be involved in tumorigenesis (J Histochem Cytochem 2009 Nov 9 [Epub ahead of print], BMC Cancer 2009;9:315)

 

End of Molecular Pathology > Polymerase Chain Reaction > Current applications

 

 

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