Assessing DNA recovery from chewing gum

Abstract

The purpose of this study was to evaluate which DNA extraction method yields the highest quantity of DNA from chewing gum. In this study, several popular extraction methods were tested, including Chelex-100, phenol-chloroform-isoamyl alcohol (PCIA), DNA IQ, PrepFiler, and QIAamp Investigator, and the quantity of DNA recovered from chewing gum was determined using real-time polymerase chain reaction with Quantifiler. Chewed gum control samples were submitted by anonymous healthy adult donors, and discarded environmental chewing gum samples simulating forensic evidence were collected from outside public areas (e.g., campus bus stops, streets, and sidewalks). As expected, results indicate that all methods tested yielded sufficient amplifiable human DNA from chewing gum using the wet-swab method. The QIAamp performed best when DNA was extracted from whole pieces of control gum (142.7 ng on average), and the DNA IQ method performed best on the environmental whole gum samples (29.0 ng on average). On average, the QIAamp kit also recovered the most DNA from saliva swabs. The PCIA method demonstrated the highest yield with wet swabs of the environmental gum (26.4 ng of DNA on average). However, this method should be avoided with whole gum samples (no DNA yield) due to the action of the organic reagents in dissolving and softening the gum and inhibiting DNA recovery during the extraction.

Forensic DNA Analysis

“…Extraction at 4 and −20 °C produced about 90% of alleles after 100 days, with the samples at −20 °C showing the highest recovery of DNA over the three-month time course . Eychner et al, who compared methods of recovering DNA from chewing gum, suggested that either swabbing or processing the gum whole can result in high amounts of recovered DNA …”

“…60 Eychner et al, who compared methods of recovering DNA from chewing gum, suggested that either swabbing or processing the gum whole can result in high amounts of recovered DNA. 61 Differential extraction involves the isolation of male sperm cells from swabs containing mixtures of male and female cells following a sexual assault. A study of the effectiveness of differential extraction techniques demonstrated the importance of documenting overall recovery.…”

Comparison of DNA yield and STR profiles from the diaphysis, mid‐diaphysis, and metaphysis regions of femur and tibia long bones

“…The lack of statistical significance in the DNA recovery value differences is likely attributed to the small sample size and large variation within each region and within donors. Great variation in small sample sizes has been observed in other DNA recovery studies as well [23,24]. In addition, no correlation was observed between the quantity of DNA recovered and the completeness of the STR profile below one nanogram of DNA.…”

Impact of DNA evidence in criminal justice system: Indian legislative perspectives

“…In addition to the touch DNA, recovery of DNA from chewing gum has also been reported (Eychner et al 2017;Tang et al 2020).…”