SFRP1 promotor methylation analysis of FTA card touch-prep samples derived from colonic polyps.

Whatman FTA® cards provide the most reliable method for DNA storage and extraction, however, the literature lacks reports on the epigenetic analysis of FTA card-derived tumor DNA. Therefore, this study aimed at demonstrating that punches from colonic adenoma samples preserved on FTA filter cards are suitable for methylation analysis by real-time methylation-specific PCR (MSP). Genomic DNA was isolated from a total of 40 sporadic colorectal adenoma samples stored on FTA cards for a median of 59.60 (range 48-72) months. After bisulfite treatment, deaminated DNA was analyzed by SYBR Green real-time MSP using primers specific for methylated and unmethylated promotor sequences of the secreted frizzled-related protein 1 (SFRP1) gene. Amplifiable DNA could be isolated from all FTA card punches while SFRP1 promotor methylation was present in 34/40 (85.0%) colorectal adenomas. Our results indicate that genomic DNA isolated from colonic tumor samples preserved on FTA cards is suitable for downstream methylation detection methodologies such as MSP even after prolonged storage periods.