The significance of amelogenin loci from toothpicks as forensic evidence for sex determination

Abstract

Objective: DNA analysis has become the gold standard of all identification methods in forensic science. There are several primary and secondary sources of DNA samples in the field of forensics. Primary sources can be obtained directly from individuals, whereas secondary sources of DNA samples include items used by someone such as clothes, toothbrushes, and toothpicks. In Asian countries such as Korea, Japan, and Indonesia, toothpicks are often used, as the tip of toothpicks used to clear food particles in the interdental regions can be utilized to capture DNA samples from saliva. The use of saliva samples for DNA analysis in sex identification is based on short tandem repeats with the amelogenin (AMG) locus. The purpose of this study was to examine the concentration and purity of DNA on toothpicks as evidence in criminal case investigations, as well as its potential as sex determination material.

Methods: Eight subjects were instructed to clean the interproximal side of their posterior teeth using a toothpick. Each toothpick sample was kept for 0 days (as a control), 14 days, and 20 days. The purity and DNA concentration of each sample were determined through DNA examination. After determining the concentration and purity of DNA from each sample, electrophoresis of the AMG loci was performed for sex determination.

Results: This study showed that the average concentration of DNA on toothpicks ranged from 425.25 to 796.25 μg/ml, and the average purity of DNA ranged from 1.09 to 1.13 μg/ml. The AMG gene produces 112 and 116 base pair amplicons from the X and Y chromosomes.

Conclusion: Sex determination using DNA can be done using AMG loci, a protein found on the sex chromosomes (X and Y). The value of DNA concentration on toothpicks could be used to support forensic identification after 20 days at room temperature.

Keywords: Amelogenin; DNA analysis; Justice; Legal identity; Sex determination.