Comparison of the DNA preservation in neutral-buffered formalin fixed paraffin-embedded tissue and in non-buffered formalin fixed paraffin-embedded tissue

Background: The preservation of optimized DNA and its extraction from formalin-fixed, paraffin-embedded (FFPE) tissues are important issues. There has been some doubt over whether 10% neutral-buffered formalin is an ideal fixation solution for DNA preservation over non-buffered formalin, as conventionally recommended. In this study, the correlation between the efficiency of DNA extraction from FFPE tissues and buffered formalin was evaluated. Methods: Several tissues with same conditions except fixatives were fixed in four different formalin solution groups and were routinely processed as paraffin-embedding protocols. DNAs were extracted from four different FFPE tissues that were stored for over 3 months and over 9 months. The quantity and quality of the DNAs were assessed with a NanoDrop ND-1000 spectrophotometer, and the polymerase chain reaction (PCR) amplification and degradation were analyzed via microchip electrophoresis. KRAS mutation analysis and microsatellite instability (BAT25) PCR were performed with each sample. Results: The results showed no remarkable difference in the four groups. Conclusions: The study findings demonstrate that DNA preservation is fairly unaffected by a neutral buffer where there is short formalin manufacture period and an adequate formalin fixation time before embedding in paraffin.