Hair DNA extraction using modified chelex method for forensic human identification

• Main Author: Lun, Wong Wai
• Format: Thesis
• Language: English
• Published: 2025
• Subjects: R Medicine; RA Public aspects of medicine
• Online Access: http://eprints.usm.my/63143/

Deoxyribonucleic acid (DNA) analysis is a cornerstone in forensic science, facilitating human identification in criminal investigations. Among biological evidence, hair is frequently encountered but presents unique challenges for DNA extraction due to its protein-rich structure and inherently low DNA content. This study focused on optimizing DNA extraction and amplification protocols for hair samples to enhance their forensic utility. Hair samples were categorized into three groups: with bulbs, without bulbs, and with unknown bulb status. Genomic DNA extraction was carried out using the Chelex® 100 resin method, further refined with the addition of Extraction Buffer for Hair (EBH) and Dithiothreitol (DTT) to improve recovery efficiency. Quantitative analysis of extracted DNA showed variability across categories, with the highest yields obtained from samples containing bulbs. To assess the forensic applicability of the extracted DNA, polymerase chain reaction (PCR) amplification targeting mitochondrial DNA (mtDNA) regions of 176 bp and 310 bp was performed. Optimized annealing temperatures and cycling conditions was established using Herculase II Fusion DNA polymerase. Agarose gel electrophoresis confirmed successful amplification of purified DNA samples, with distinct bands corresponding to the targeted mtDNA regions. The findings highlight the utility of mtDNA extracted from hair for human identification, especially in situations where traditional biological evidence is unavailable. Although samples with bulbs yielded higher DNA concentrations, successful amplification was also achieved in samples without bulbs and with unknown bulb status, demonstrating the versatility of this approach. Future investigations should explore factors influencing DNA yield, such as hair growth phases, and incorporate nuclear DNA analysis to enhance individual specificity. This study advances forensic science by refining hair DNA recovery and amplification techniques, advancing the reliability of hair evidence in criminal investigations