Tissue Requirements and DNA Quality Control for Clinical Targeted Next-Generation Sequencing of Formalin-Fixed, Paraffin-Embedded Samples: A Mini-Review of Practical Issues

Most molecular pathology laboratories perform mutational analyses to diagnose somatic cancer mutations and evaluate therapeutic options on formalin fixed paraffin embedded (FFPE) samples as daily practice using various methods. Recent studies show that targeted next-generation sequencing (NGS) is a promising diagnostic method with many benefits including simultaneous detection of multiple mutations in various genes in a single test. High quality DNA is essential for an efficient and successful NGS performance. However, low tumor tissue percentage and low DNA quality are the main limitations to use FFPE DNA for NGS assay. We reviewed and discussed the required tissue amount for the NGS assay, the effect of formalin fixation on DNA integrity, and the method for reduction of formalin-induced sequencing artifacts. We also review DNA extraction methods, DNA quality control methods and quality control workflow for nucleic acids and libraries. This review provides an overview for molecular pathology laboratories or researcher considering NGS to detect somatic cancer mutations using small FFPE samples.