Selective enrichment of human DNA from non-human DNAs for DNA typing of decomposed skeletal remains

The degraded or decomposed body remains pose serious challenges for successful short tandem repeat (STR)-based DNA typing for human identification because of contamination with non-human DNAs and environment-induced changes. Owing to their tropical environment, which results in robust microbial infestation, obtaining good quality and quantity of human DNA for body identification by DNA profiling has not been very successful in those regions. To address this issue, we attempted to selectively recover the human DNA from the mixture of non-human DNAs by employing the biotinylated oligonucleotides, designed complementary to the regions flanking the STR loci to selectively capture the respective STR loci that are used for DNA profiling. Initially, the fragmented human DNA was hybridized with the biotinylated oligos, followed by conjugation of biotin with streptavidin-coated paramagnetic beads. After extensive washing to remove non-specific binding, repeat-containing DNA fragments were eluted employing a magnetic particle concentrator. Such repeat-enriched DNA fragments were subjected to PCR amplification to analyze STRs employing commercial human DNA typing kits. Our preliminary analysis has shown that there was selective recovery of STR-containing human DNAs when biotinylated oligos were used. (C) 2009 Elsevier Ireland Ltd. All rights reserved.