[DNA extraction and Southern blot analysis in paraffin embedded material]

DNA was extracted from formaldehyde fixed and paraffin embedded tissue by the use of a modified extraction protocol. In all cases the recovered DNA was more degraded than DNA from fresh or frozen tissue. Fixation times of more than 4 days made it impossible to use the extracted DNA for Southern Blotting; DNA from paraffinized tissues not older than 1 or 2 years could be used for Southern Blotting after digestion with restriction enzymes, but we did not succeed in showing bands with restriction fragments more than 10 kb in length. We conclude that SBA analysis for malignant lymphomas with DNA extracted from routinely paraffin-embedded tissues isn't possible, because the restriction fragments looked for are in many cases longer than 10 kb.