Evaluation of long-term storage effects on buccal cell DNA from untreated cards for STR profiling

Abstract

The success of DNA profiling using long-term stored samples depends on the amount and quality of their recovered DNA templates. Physical and biochemical factors such as microbial activity, humidity and temperature contribute to DNA degradation. In this study, we used genomic DNA extracted from buccal cell samples that were stored for more than 4 years on Bode Buccal DNA Collector™ cards (Bode Technology, Virginia, USA) for typing 27 and 24 short tandem repeat (STR) loci using Powerplex® Fusion 6C system (Promega Corporation, Madison, USA) and Globalfiler™ Express kit (Thermo Fisher Scientific, USA), respectively. Our results demonstrated that the Buccal DNA Collector can be used as a collection medium for buccal swab samples that are not immediately analyzed or those that need to be retrospectively analyzed. There is a sign of DNA degradation which might well be expected because buccal cell samples were deposited on untreated filter paper and have been stored for a long period (> four years) at room temperature. However, STR allele calls were obtained from most of the buccal cell samples, especially when typed using the Powerplex® Fusion 6C system kit.