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 paraffin-embedded human tissues enhances opportunities to study breast, lung and other cancer risk factors, We report herein a simple and fast protocol for the extraction of genomic DNA from these sources, Using a phenol-based extraction method, the recovery for DNA is quantitative and reproducible, DNA yields in serum (250 mu l) were between 162 and 1060 ng (It = 18 subjects), in plasma (250 mu l) were between 165 and 375 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 formaldehyde 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 for cancer susceptibility marker genes such as CYP1A1 (exon 7), CYP2E1 (Dra1, Rsa1), GSTM1 and NAT2 [NAT2*5A ((CT)-T-481), NAT2*6A (G(590)A), NAT2*7A (G(857)A)I] Genotyping results from the serum and paraffin-embedded tissues compared favorably to results from archived freshly frozen tissues, where concordance was 98% for serum, 100% for ethanol-fixed embedded tissues, and 97% for formaldehyde-fixed and paraffin-embedded tissues, This facile method will allow for the use of archived tissue samples of prospective cohort and other studies where intact DNA was not previously available.