Quantity and Quality Assessment of DNA Extracted from Saliva and Blood

Background: Saliva has been suggested as an attractive resource for evaluating physiological and pathological conditions in humans. This study aims to evaluate saliva sampling as an alternative to blood sampling for molecular testing. Methods: We compared the yield, purity, and performance of DNA isolated from blood to that isolated from saliva using the non-invasive collection kit (Oragene (R) DNA OG500 and OG575 kit). Saliva DNA was extracted by manual purification and QIAamp DNA mini kit. Blood DNA was isolated by salt-precipitation and DNAzol reagent. We also evaluated the quality of saliva DNA by PCR-based analysis. Results: We found that the DNA yield from saliva (7.8 mu g/0.5 mL saliva sample) from the manual purification method was comparable to the DNA yield from blood by the salt precipitation method (7.4 ug/0.5 mL blood sample). DNA extracted from saliva and blood were both of high purity (A(260/280) >1.70). Genotype results (PCR-RFLP and direct sequencing) for all sets of blood-saliva DNA samples were in 100% concordance. Conclusions: Saliva samples, when extracted by the manual purification method, provide a similar amount of human DNA as compared to the amount obtained from blood. Saliva is a viable alternative DNA source for genotyping studies. (Clin. Lab. 2012;58:307-312)