SERUM, PLASMA AND PARAFFIN-EMBEDDED TISSUES AS SOURCES OF DNA FOR STUDYING CANCER SUSCEPTIBILITY GENES

The ability to isolate DNA from archived human serum, plasma and paraf fin-embedded human tissues enhances opportunities to study breast, lun g and other cancer risk factors, We report herein a simple and fast pr otocol for the extraction of genomic DNA from these sources, Using a p henol-based extraction method, the recovery for DNA is quantitative an d reproducible, DNA yields in serum (250 mu l) were between 162 and 10 60 ng (It = 18 subjects), in plasma (250 mu l) were between 165 and 37 5 ng (it = 5 subjects) and in embedded tissues (5-mu m thick sections for ethanol fixed, and between 5- and 20-mu m sections for formaldehyd e fixation) were between 1 mu g and 11.7 mu g (it = 32 subjects), The extraction method was combined with newly designed PCR-based assays fo r cancer susceptibility marker genes such as CYP1A1 (exon 7), CYP2E1 ( Dra1, Rsa1), GSTM1 and NAT2 [NAT25A ((CT)-T-481), NAT2*6A (G(590)A), NAT27A (G(857)A)I] Genotyping results from the serum and paraffin-emb edded tissues compared favorably to results from archived freshly froz en tissues, where concordance was 98% for serum, 100% for ethanol-fixe d embedded tissues, and 97% for formaldehyde-fixed and paraffin-embedd ed tissues, This facile method will allow for the use of archived tiss ue samples of prospective cohort and other studies where intact DNA wa s not previously available.