Nucleic Acids Extraction from Formalin-Fixed and Paraffin-Embedded Tissues

Formalin-fixed paraffin-embedded (FFPE) tissues are an important sample source for ret‐ rospective studies. Despite its ability to preserve proteins and cell morphology, formalin hinders molecular biology tests since it fragments and chemically modifies nucleic acids, especially RNA. Although several studies describe techniques that allow extracting nu‐ cleic acids from FFPE tissues, so far there is no consensus in the literature about the best protocol to be used in this type of material. Thus, the current chapter aims to describe the factors affecting the FFPE tissue nucleic acid extracting process, compare the available protocols and to describe the modifications developed by our group in some protocols. Such modifications enable nucleic acids obtainment in satisfactory quantity and quality for molecular biology studies.