DNA extraction from archived specimens by sonication

The analysis of DNA from archived tissues is an important clinical research and diagnostic tool. The analyses of these preserved tissues that are most commonly formalin-fixed and paraffin-embedded allow for the retrospective study of a variety of genetic changes, or even the presence of infectious agents. Prior to polymerase chain reaction (PCR), the genetic analyses of fixed tissues were carried out using in situ hybridization, dot-blot hybridization, or Southern blotting. These methodologies have traditionally provided some degree of success, but are sometimes limited in sensitivity, involve complex procedures, or cannot detect degraded DNA, which is found in old-fixed tissues. PCR analysis provides a simple and sensitive method for the analysis of DNA from fixed tissues. A number of methods exist for isolating DNA from formalin-fixed, paraffin-embedded tissues, but the best procedures in terms of reliably releasing DNA involve a large number of solvent extractions, centrifugations, and long digestion periods with enzyme buffers. A method has been developed that quickly and efficiently extracts DNA from paraffin-embedded tissue. This method utilizes a sonicating water bath to disrupt the tissue samples and such samples can be prepared in less than 30 min with only solvent extraction in a minimum of steps.