A new “miniSTR-multiplex” displaying reduced amplicon lengths for the analysis of degraded DNA

Abstract

A multiplex PCR was designed for the loci D2S1338, D16S539, D18S51, TH01 and FGA using redesigned primers in order to reduce the lengths of the amplification products compared to the designs used in commercially available multiplex PCR kits, also including amelogenin. The new PCR primers were used to amplify highly degraded DNA from casework samples, which had shown no or only poor results for these loci in previous analyses with standard primer sets. The application of the new miniSTR-multiplex resulted in an increased overall typing success rate for degraded DNA samples. In a concordance study between the conventional and the newly designed primers, no genotype differences were revealed in 124 randomly selected individuals.

Scope of X-Chromosomal MiniSTRs: Current Developments

“…The results were collated and analysed and, in general, mini-STR systems were shown to be the most effective [26]. Since then, a number of other studies have demonstrated that successful analysis of degraded DNA specimens from mass disasters or compromised forensic evidence improves with smaller-sized PCR products [8,10,12,14,[27][28][29][30][31]. The TIMELINE (Figure 1) shows the progress of ChrX miniSTRs over the years [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46].…”

“…Bacteria are the main agents on land while fungi are responsible for oceanic degradation [6,7]. Slightly degraded samples can be typed by traditional STRs, but may yield negative results as the fragmentation increases [8][9][10]. Conventional STRs have a size range of 100-400 bp most of which consists of flanking sequences on both sides of the repeat region.…”

Increasing the discrimination power of forensic STR testing by employing high-performance mass spectrometry, as illustrated in indigenous South African and Central Asian populations

“…This is known to result in an increased success rate when degraded DNA is investigated [17] and therefore highly appreciated in forensic analysis.…”

The influence of high temperature on the possibility of DNA typing in various human tissues

“…As a result of the high temperature exposure, the DNA available for analysis is highly thermally degraded and frequently present in very few copies. A trace amount of template DNA available for amplification very frequently leads to different types of artifacts such as a lack of amplification of particular alleles (allele drop-out) or loci (loci drop-out) [7][8][9][10]. The problem of the effect of high temperature on biological material and the possibility of DNA identification has been rarely mentioned.…”

“…DNA yield and stability in different soft human tissues vary substantially [14] and are highly dependent on physical and chemical factors. In many cases reduction of amplicon size, like substituting STR (Short Tandem Repeats) with miniSTR loci or SNPs, can drastically improve DNA typing results [9,11,12,15].…”