Modifications of human and viral deoxyribonucleic acid by formaldehyde fixation.

Abstract

The loss of PCR product is related to fixation time and PCR-product-length, probably because of the rate of denaturation followed by modification of DNA. Contrary to what has previously been assumed, formaldehyde neither fragments nor reduces the quantity of DNA, but rather changes the structure of DNA. Different tissues may also react differently with formaldehyde, in part because of different tissue fixation gradients. When the PCR product is shorter than 200 bp, DNA isolated from paraffin-embedded tissues fixed with 4% formaldehyde can be useful to any kind of PCR product analysis.