Feasibility of collecting buccal cell DNA by mail in a cohort study

This study assessed the feasibility of obtaining buccal cell DNA by mail fr om participants in a large, community-based cohort study in Hawaii. Mouthwa sh collection kits were sent to a total of 355 randomly selected Japanese, Caucasian, and Hawaiian cohort members. Subjects were requested to swish 10 ml of mouthwash in their mouth for 60 s and expel it into a collection cup , which they mailed back to our laboratory. Half of the subjects were reque sted to collect a second sample. After up to two mailings and two reminder phone calls, two-thirds of the subjects returned a sample. The participatio n rate was lower for Hawaiians (59.0%) than for Caucasians (68.1%) and Japa nese (76.3%). Participation was not affected by requesting two specimens. P articipants did not differ from the total sample in terms of education and smoking status. The mean DNA yield was lower in females (41.7 mug) than mal es (53.4 mug) and in Japanese (37.8 mug) as compared with Hawaiians (51.9 m ug) and Caucasians (54.5 mug). For subjects who returned two samples, the D NA yields were similar when both specimens were extracted in the same batch . All samples were successfully genotyped for polymorphisms in the CYP1A1, CYP2E1, GSTM1, GSTT1, and NQO1 genes by PCR-RFLP, From these and previous d ata, we conclude that, in situations where blood samples cannot be obtained , mail collection of mouthwash samples should be considered because it yiel ds substantial amounts of high-quality genomic DNA for large numbers of stu dy subjects.