Assessment of the most reliable sites in mandibular bone for the best deoxyribonucleic acid yield for expeditive human identification in forensics.

Background: In recent years, the techniques used to identify human remains post accidents, trauma or in case of criminal investigation have been expanded, improved and rendered more complex by the emergence of technologies based on deoxyribonucleic acid (DNA) analysis. In the head and neck area, tooth has been proven to be the best quantitative source for DNA but in certain cases where the mandible specimen is edentulous or the tooth is extensively destroyed with caries, large dental restorations, mobile, or if they show any perimortem or postmortem fractures, sampling of such tooth specimen is usually avoided. In such situations, bone is considered the next best site for DNA analysis. Mandible being the largest, strongest and dense cortical bone is the most prominent facial bone that can be easily disarticulated. It can be analyzed for the best short tandem repeat (STR) segment qualitative amplification using polymerase chain reaction (PCR) technique for forensic analysis which can be used for gender and age determination.

Aim: The aim of this study is to determine the best site for optimum quantitative and qualitative yield of DNA for amplification using specific and standard STR segment by conventional PCR technique.

Methodology: Fifteen mandibular samples exposed to different environmental conditions were collected. Bone pieces of 1 cm × 1 cm were cut from each mandible from three sites, i.e., the ramus, angle and body, wherein the genomic DNA was isolated and was subjected to PCR using restricted number of 25 cycles.

Results: The STR segment D3S1358 from clone RP11-438F9 used for the study showed very good amplification in restricted number of PCR cycles in the ramus region with number of repeats in every 15th genomic region.

Conclusion: This study highlights the use of mandibular bone for the expeditive human identification. As per the study, the ramus of the mandible gave high quantitative and qualitative yield of DNA with thick amplification band of the STR segment as compared to the body and angle of the mandible. Thus ramus of the mandible can be preferred over other sites for molecular forensic investigations.