Comparison of Roche Cell-Free DNA collection Tubes® to Streck Cell-Free DNA BCT®s for sample stability using healthy volunteers

Objectives: To compare the Roche Cell-Free DNA Collection Tubes (R) against the Streck Cell-Free DNA BCT (R) s for sample stability using Cell Free DNA (cfDNA) from healthy volunteers (n = 20). Design & methods: Whole blood was drawn into five Roche and five Streck tubes per volunteer, stored at room temperature and processed at five different time points (Days 0, 4, 7, 10 and 14). One volunteer had blood drawn into x10 K(3)EDTA tubes to observe the effect of no preservation buffer on White Blood Cell (WBC) lysis. DNA was extracted from the plasma and the concentration (ng/mu L) measured using the Qubit Fluorometer (R) at each time point. The eluted DNA was further analysed by capillary electrophoresis to determine the proportion of cfDNA and gDNA contamination in the samples over the 14 days. Results: There was no difference in individual (p = 0.097) and median paired (p = 0.26) DNA concentration across the five time points between the two tubes. However, a difference was observed for samples in the Roche tubes for pair days 0-7 (p = 0.01), 0 to 10 (p = 0.046) and 0 to 14 (p = 0.0016) in contrast to the Streck tubes after adjustment for multiple testing. Conclusion: The findings of this study indicate that the Roche Cell-Free DNA Collection Tubes (R) are a suitable alternative for sample collection and storage at room temperature, albeit for a duration of less than 7 days.