Abstract: Objective To evaluate the feasibility of STR genotyping from trace epithelial cells on fountain pen and to discuss the impact of conservation time on DNA typing. Methods Seven fountain pens were separately used by each of the 17 volunteers 20 minutes per day for a month and then were preserved on day 1, 3, 5, 7, 14, 21, and 28. DNA was extracted from the epithelial cells on fountain pen by silicon bead and was genotyped by Identifier kit. The corresponding control samples were buccal swabs of the above volunteers. The detectable numbers of loci were counted for assessment. Results There were statistically significant differences in the DNA genotyping by detectable numbers of gene loci between buccal swabs and epithelial cells on fountain pen of different conservation times (P<0.01). The differences of detectable numbers of loci between the epithelial cells on fountain pen preserved on day 1, 3, 5, 7, 14, 21, 28 and the corresponding oral swabs were also statistically significant (P<0.01). More than 12 loci could be successfully genotyped in 41.2% samples from the epithelial cells on fountain pen if the tests were performed within 24 hours. Conclusion The trace epithelial cells on fountain pen can be used as biological samples for personal identification, but the conservation time would have influence on the results of DNA genotyping.

Key words: Forensic biology, epithelial cells, DNA, STR multiplex amplification