THE EFFECT OF FIXATION TYPE ON DNA EXTRACTED FROM PARAFFIN-EMBEDDED TISSUE FOR PCR STUDIES IN DERMATOPATHOLOGY

Background: Amplification of nucleic acids from paraffin-embedded mate rial by the polymerase chain reaction (PCR) is widely used to detect v iral genomes, clonal gene rearrangements and oncogene mutations in ski n specimens. Fixation with embedding of skin tissue is a procedure tha t has a profound effect on its molecular arrangement. Objective: The a im of this study was to determine the effect of different fixatives on the PCR amplification of DNA. Methods: We fixed randomly chosen fresh pathologic skin specimens in formalin, ethanol and Histochoice for 24 and 72 h and then embedded the tissue in paraffin. DNA was extracted from the paraffin-embedded tissues and used as template for amplificat ion, producing 530- and 760-bp fragments of the phosphoglycerokinase g ene. Results: Our results indicate that PCR can be performed with exce llent results on ethanol- and Histochoice-fixed, paraffin-embedded ski n tissue with a rate of success comparable to that using fresh tissues ; formalin-fixed tissue gave slightly less satisfactory results. Concl usion: This investigation corroborates previous reports investigating the effect of ethanol and formalin fixation on DNA amplification by PC R. Moreover, this is the first study showing that DNA extracted from t issue fixed with Histochoice is suitable for PCR gene amplification.