Direct STR typing from human bones

Area of Science:

• Forensic Science
• Molecular Biology
• Anthropology

Background:

• Traditional STR analysis of bone samples is hindered by time-consuming decalcification and complex DNA extraction.
• Efficient DNA profiling from skeletal remains is crucial for identification in forensic and archaeological contexts.
• Streamlining bone DNA analysis can significantly reduce turnaround times in forensic casework.

Purpose of the Study:

• To develop and optimize a direct short tandem repeat (STR) typing protocol for bone samples.
• To evaluate the efficiency and performance of the direct STR typing protocol across various bone elements.
• To compare the direct STR typing method with conventional STR typing for casework samples.

Main Methods:

• Optimization of bone sample quantity (100 mg powder) and buffer conditions (300 µL PBS) for direct DNA amplification.
• Heat treatment at 98°C for three minutes to obtain supernatant for DNA amplification.
• Evaluation of two commercial PCR kits (Identifiler™ Plus and IDplex Plus) and testing on seven bone elements (N=105).

Main Results:

• The optimized direct STR typing protocol achieved 94.3% high partial to full profiles across seven bone elements.
• IDplex Plus kit demonstrated superior allele recovery and peak height compared to Identifiler™ Plus.
• No significant difference in allele counts was observed between direct and conventional STR typing in casework samples (up to 7-year PMI).

Conclusions:

• The developed direct STR typing protocol is rapid, convenient, and safe, significantly streamlining bone DNA analysis.
• The protocol shows consistent performance across different bone elements, with cancellous bone yielding better results than compact bone.
• This method has the potential to enhance STR typing efficiency from challenging bone samples in forensic investigations.