Evaluation of the methodology for applying Pressure Cycling Technology in nuclear DNA genotyping extraction from human nail

Objective: To apply pressure cycling technology (PCT) in nuclear DNA extraction from human nails, and complete the evaluation of corresponding extraction methodology. Methods: Nails samples collected from 10 volunteers were divided into two groups (10 samples for each group). Both groups of samples were cut into 1mm by 1mm pieces, and then cleaned with sterile water which was prepared in 10% bleaching powder, 10% SDS. The group of samples served as experimental group was processed with pressure cycling technology, while control group was not. DNA extracted from both experimental group and control group were used for multiplex amplification and STR typing, to evaluate the effect of pressure cycling technology. Two additional groups containing 5 human nail samples each were set to evaluate the impact of aforementioned cleaning methods on exogenous DNA removal. The experiment group was immersed in blood, while the control group was immersed in deionized water. Results: 7 out of 10 samples in experimental group shown higher DNA extraction yield than corresponding control group, but the statistical treatment indicates there is no statistically significant difference between experimental group and control group (P > 0.05); Samples with DNA extraction > 0.026ng in both groups got complete STR typing, and the results were exactly aligned with corresponding mouth swab samples. Samples with or without blood contamination can avoid exogenous DNA contamination by applying aforementioned cleaning methods more than twice. Conclusion: PCT along with aforementioned cleaning methods can significantly improve the efficiency of DNA extraction from human nails, and the accuracy of DNA genotyping can be ensured by litter impact from exogenous DNA contamination.