Use of Buccal Cells Collected in Mouthwash as a Source of DNA for Clinical Testing

Abstract

Abstract Context.—To maximize the participation rate in population genetic studies, alternatives to invasive whole blood collection are increasing. One such alternative is buccal epithelial cell collection, which, in contrast to venipuncture and finger sticks, is painless. Buccal cells, if collected and purified efficiently, offer an acceptable source for DNA to be used in research and clinical applications. Objective.—To develop a noninvasive sampling method for collecting cells for routine DNA testing in a clinical laboratory setting. Design.—Five factors were used to evaluate several brands of mouthwash: (1) compatibility with the DNA purification chemistry, (2) DNA yield, (3) DNA quality, (4) DNA stability at room temperature, and (5) mouthwash taste. Next, an optimization study was undertaken to maximize DNA yield. Finally, a validation study was undertaken with the optimized protocol to test a panel of 14 donors for DNA yield and performance and to test for the stability of DNA held in mouthwash. Setting.—Industrial research and development laboratory. Results.—Of 5 mouthwashes tested, Scope brand mouthwash received the highest overall ranking. The addition of proteinase K and glycogen to the protocol significantly enhanced DNA yields, with a test panel (n = 14) giving a range of 12 to 60 μg of DNA per donor. In a 4-week room temperature stability study, the DNA in mouthwash samples was found to be stable for at least 2 weeks. Conclusion.—A clinically validated DNA purification chemistry was adapted to a noninvasive specimen collection method. This method used a commercially available mouthwash, Scope, to collect buccal epithelial cells for the preparation of high-quality DNA in high yield.