[Comparison of Different Pretreatment Methods for DNA Extraction from Teeth].

OBJECTIVE: To compare the concentration of teeth DNA extracted by three different pretreatment methods and to explore a simple, economical and practical pretreatment method with high concentration of extracted DNA from teeth. METHODS: A total number of 21 molars were collected from 7 corpses. The pretreatment of 3 molars from each individual was randomly performed by tooth crumb method, ball-milling method and liquid nitrogen milling method and 50 mg tooth crumb was weight and DNA was extracted by AutoMate Express forensic DNA extraction system. Subsequently, the concentration of DNA and corresponding STR genotyping of three methods were compared. RESULTS: The DNA concentration extracted by tooth crumb method, ball-milling method and liquid nitrogen milling method was 0.055 6-1.989 1 ng/µL, 0.036 6-1.175 6 ng/µL and 0.037 8-1.249 0 ng/µL, respectively. The DNA concentration obtained by tooth crumb method was higher (P < 0.05) and the success rate of STR genotyping was high. CONCLUSION: Combined with AutoMate Express forensic DNA extraction system, tooth crumb method is an efficient and feasible method to extract DNA from teeth, which can be applied in forensic practice.

Touch DNA of shed skin cells from the deployed airbag to address drunken driving crimes.

In the criminal cases of driving under the influence (DUI), DNA evidence can be collected from the deployed airbag of the motor vehicle and submitted to the crime lab for touch DNA analysis. The evidence can be acquired when the skin cells are observed on the surface of the airbag in a traffic accident. However, the low quantity or quality of the evidence collected from a crime scene prevents further identification analysis in many cases. In the current study, we reported a case of identifying touch DNA extraction from the shed skin cells from the deployed airbag of a motor vehicle. We managed to collect DNA evidence from the shed skin cells in an airbag using a proper approach of collection and extraction. The 5.87 ng of extracted DNA was sufficient for genotyping and forensic identification, which helped to identify the driver of the car in collision with a pier in the street. In DUI cases and other traffic accidents, therefore, the amount of touch DNA extracted from the deployed airbag can be sufficient for DNA marker genotyping and further analysis.