Determinants of DNA yield and quality from different non-invasive sampling methods

Aim: The purpose of this study was to determine the DNA yield and quality from different non-invasive sampling methods and to identify the method which gave the highest DNA yield. Method: Thirty-eight volunteers had been recruited in this study where blood, buccal cells and saliva were collected using various collection techniques. Buccal cells were collected by 1) cytobrush and 2) saline mouth rinsing or “swish”. Meanwhile saliva was collected by passive drooling method. Upon processing the white blood cell (WBC), buccal cells and saliva samples, DNA extraction was performed according to the manufacturer’s protocol. Quantification and quality (DNA ratio at A260/A280) of the extracted DNA were determined using NanoDropND-1000®. T-test was performed to compare means between DNA obtained from various collection methods. Results: DNA yields from buccal cells collected with cytobrush, “swish”. Saliva and WBC (mean ± SD) were (8.2 ± 5.9)ng/μl, (28.2 ± 14.9)ng/μl, (5.9 ± 9.5)ng/μl and (105.3 ± 75.0)ng/μl respectively. Meanwhile the mean DNA ratio at A260/A280 for cytobrush, “swish”, saliva and WBC were 2.3, 2.0, 1.7 and 1.8 respectively. Post hoc test with Bonferroni correction suggested that DNA yield from “swish” technique exhibited the least mean different as compared to the DNA extracted from WBC (p<0.05). There was no significant difference in the mean quality of the DNA extracted from WBC, saliva and buccal cells collected in these non-invasive methods (p=0.323). Conclusion: The “swish” technique of obtaining buccal cells yielded the highest amount of DNA and was of the quality of DNA extracted from blood sample.