A high frequency of sequence alterations is due to formalin fixation of archival specimens.

摘要: Genomic analysis of archival tissues fixed in formalin is fundamental importance biomedical research, and numerous studies have used such material. Although the possibility polymerase chain reaction (PCR)-introduced artifacts known, use direct sequencing has been thought to overcome problems. Here we report results from a controlled study, performed parallel on frozen formalin-fixed material, where high frequency nonreproducible sequence alterations was detected with tissues. Defined numbers well-characterized tumor cells were amplified analyzed by DNA sequencing. No found In material up one mutation artifact per 500 bases recorded. The chance artificial mutations inversely correlated number PCR—the fewer cells, more artifacts. A total 28 recorded, which 27 C-T or G-A transitions. Through confirmational independent amplification products can be distinguished true mutations. However, because this problem not acknowledged earlier, presence may profoundly influenced previously reported including those inserted into databases.