Comparison of methods for collection of DNA samples by mail in the Black Women's Health Study

PURPOSE: The authors compared approaches to participants and methods of collecting buccal cell samples by mail in the Black Women's Health Study, a follow-up study of geographically dispersed African-American women. Outcomes of interest were within group participation rates, yield of DNA, and PCR success. METHODS: Six hundred fifty six participants were randomized to four groups: Groups 1 and 2 used the cheek swab method and Groups 3 and 4 used the mouthwash swish method. Groups 1 and 3 were mailed collection kits together with consent forms, whereas Groups 2 and 4 were mailed a kit only after returning a signed consent. RESULTS: Participation rates were similar regardless of the method used for sample collection or mailing of the kits: samples were returned by 40% of Group 1, 37% of Group 2, 36% of Group 3, and 35% of Group 4. The median DNA yield was 3693 ng/sample for the swab method and 10,077 ng/sample for the mouthwash swish method (p < 0.001). PCR analyses were successful in 98% of mouthwash samples and 94% of swab samples. CONCLUSION: Because of its higher yield of DNA, the mouthwash swish method is preferable for collection of buccal cell samples by mail. (C) 2003 Elsevier Inc. All rights reserved.