Automated genomic DNA extraction from saliva using the QIAxtractor

Abstract

Background: Venipuncture is an invasive procedure to obtain whole blood in order to obtain high quality and sufficient amounts of genomic DNA. Obtaining DNA from non-invasive sources is preferred by patients, medical doctors and researchers. Saliva collected with cotton swabs (Salivette) is increasingly being used to study chemical compounds, and it can also be a source of DNA. However, extracting DNA from Salivettes is very laborious and time consuming. Therefore, we developed a protocol for automated genomic DNA extraction from saliva collected in Salivette using the QIAxtractor.

Methods: Saliva (0.1-2.0 mL) was collected by chewing on a Salivette for 1-2 min. A total of 70 samples, collected from healthy volunteers, were extracted with the QIAxtractor robot and a Qiagen DX reagent pack. Quantity and quality was assessed using UV spectrometry and real-time polymerase chain reaction (PCR) (substitution at position -729 in the CYP1A2 gene).

Results: The average DNA concentration from the saliva samples was 6.0 microg/mL (95% CI 5.4-6.6 microg/mL). In 100% of the saliva samples, PCR products were detected with an average cycle threshold of 23.1 (95% CI 22.6-23.6).

Conclusions: DNA can be extracted in sufficient amounts from Salivette with a fully automated system with a short turnaround time. Real-time PCR can be performed with these samples.