[Analysis of different methods of extracting DNA from paraffin-embedded tissues and the application of nest PCR].

The aim of this research was to explore the most optimal method of DNA extraction from formalin-fixed, paraffin-embedded (FFPE) tissues, and to improve the amplification of long fragments with the method. Three methods, one step method, phenol-chloroform extraction method, and genomic DNA purification kit method, were employed to extract DNA from twenty normal thyroid tissues which were fixed with formalin and embedded with paraffin. The highest proportionality of OD260/OD280 in the examples was obtained by phenol-chloroform extraction method, 1.703 +/- 0.086, compared to the results of the other two methods. As for the long DNA segments amplification, the achievement ratio of one step method, phenol-chloroform extraction method and genomic DNA purification kit method were 0%, 5% and 10%, respectively, by traditional PCR method, but 0%, 95% and 85% respectively by the nest PCR. We have found that the best process of extracting DNA from FFPE is digesting by proteinase K and purifying by phenol-chloroform, and it is effective to amplify long DNA segments from FFPE by nest PCR.