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ANALYSIS OF REDUCED SIZE STRAMPLICONS AS TOOLS FOR THE STUDY OF DEGRADED DNA

Abstract:

Polymorphic Short Tandem Repeats (STRs) markers have become a very useful tool in forensic analysis of human DNA. Multiplex PCR amplification of STR loci enables to obtain genetic information from almost any source of biological material. However, some forensic evidences, can be so extremely degraded (e.g. certain mass disasters, old and bad preserved remains, etc) that STR typing is unsuccessful. In these situations DNA typing can be challenging and it could be difficult to obtain quality profiles (ej: loss of signal of larger sized loci is frequently observed as a result of DNA fragmentation, etc.). Recent efforts have focused on the use of nuclear Single Nucleotide Polymorphism (SNP) markers as an alternative and more recently, on reducing the size of STR markers (miniSTRs). The development of miniSTRs is accomplished by simply moving the primer binding sites closer to the STR repeat region, and creating DNA fragments that are shorter than traditional STR markers. MiniSTRs markers have shown to be very successful at recovering DNA profiles from highly degraded samples The possibility of obtaining nuclear MiniSTRs profiles corresponding to conventional STR markers is also considered a great advantage as most of the National intelligence DNA banks are based on them. In this chapter we will review the development and use of miniSTRs loci in forensic genetics from its first application in the analysis of Branch Davidian fire in Waco to its incorporation in commercial kits. We will not only focus on autosomal miniSTRs but also on the recent development of miniY-STRs and miniX-STRs. Advantages and disadvantages of these markers in Forensics will be considered and compared to those of traditional STR markers. Finally, we will review potential applications and future perspectives of their use in Forensic Genetics.