An assessment of preserved DNA in decomposed biological materials by using forensic DNA profiling

Abstract

Abstract Background DNA profiling for the victim identification in several forensic situations is mostly challenging due to a high degree of degradation or due to a high level of intermingling of remains. There are many intrinsic and extrinsic factors involved in the postmortem decay of tissues. Forensic DNA analysts come across a variety of samples ranging from stain samples to visceral material to bone or teeth. The amount and quality of DNA recovery are highly variable/challenging in dealing such forensic evidence. Material and methods In the present study, two different types of postmortem tissues (brain and prostate/uterus) along with teeth of 20 naturally decomposed human bodies were analysed. DNA extraction has been performed using the phenol-chloroform extraction method. Further, the extracted samples have been subjected for quantitative analysis using RT-PCR. Samples were amplified using the PowerPlex® 21(PP 21) multiplex system and were genotyped using capillary electrophoresis in 3500XL Genetic Analyzer. Results A perfect short tandem repeat (STR) profile has been generated from all the teeth samples. In most of the cases, brain tissue samples also provided an optimal profile. In contrast, prostate tissue samples gave partial amplification at almost all the samples. These findings were further evaluated by DNA profile quality measures for the studied samples. Conclusion The present study may provide a platform to effectively evaluate forensic samples that contain small or degraded DNA template. The multiplex autosomal STR loci PP 21 system used in the study is efficient enough for typing such degraded samples with high sensitivity and discrimination power.

Keywords

• Forensic
• DNA typing
• STR multiplex
• PowerPlex 21TM
• Degraded samples