Tumoural specimens for forensic purposes: comparison of genetic alterations in frozen and formalin-fixed paraffin-embedded tissues

Abstract

In certain circumstances, tumour tissue specimens are the only DNA resource available for forensic DNA analysis. However, cancer tissues can show microsatellite instability and loss of heterozygosity which, if concerning the short tandem repeats (STRs) used in the forensic field, can cause misinterpretation of the results. Moreover, though formalin-fixed paraffin-embedded tissues (FFPET) represent a large resource for these analyses, the quality of the DNA obtained from this kind of specimen can be an important limit. In this study, we evaluated the use of tumoural tissue as biological material for the determination of genetic profiles in the forensic field, highlighting which STR polymorphisms are more susceptible to tumour genetic alterations and which of the analysed tumours show a higher genetic variability. The analyses were conducted on samples of the same tissues conserved in different storage conditions, to compare genetic profiles obtained by frozen tissues and formalinfixed paraffin-embedded tissues. The importance of this study is due to the large number of specimens analysed (122), the large number of polymorphisms analysed for each specimen (39), and the possibility to compare, many years after storage, the same tissue frozen and formalin-fixed paraffin-embedded. In the comparison between the genetic profiles of frozen tumour tissues and FFPET, the same genetic alterations have been reported in both kinds of specimens. However, FFPET showed new alterations. We conclude that the use of FFPET requires greater attention than frozen tissues in the results interpretation and great care in both preextraction and extraction processes.

Characterization of human breast tissue microbiota from core needle biopsies through the analysis of multi hypervariable 16S-rRNA gene regions

“…This finding may be attributed to procedures used for microbial gDNA isolation and analysis, which likely allow for a greater recovery of useful gDNA and for its more accurate analysis. Indeed, samples were obtained under aseptic conditions and were freshly processed to limit contamination and genetic material loss as is found in frozen and formalin-fixed paraffin-embedded tissues 37 . Moreover, most gDNA from living microbes was isolated, removing non-target DNA as free floating and human DNA 38 .…”

Long-term room temperature preservation of corpse soft tissue: an approach for tissue sample storage

“…Moreover, handling and preserving large numbers of samples requires a large volume of freezing equipment, which is not always available in disaster-challenged areas. Several specific methods for specimen preservation have been described, some of which exhibit adequate storage capacity for different tissues, for example, cryopreservation [ 7 ], formalin-fixed paraffin-embedded tissue, despite producing the disadvantage of irreversible changes in the molecular structure [ 9 , 11 ], salt water [ 10 ], alcohol-based tissue fixatives, dimethylsulfoxide (DMSO), commercial kits such as the Oragene DNA self-collection kit (DNA Genotek, Ottawa, Ontario, Canada) [ 11 - 14 ], LST buffer [ 12 ], and RNA later (Ambion, Austin, TX, USA) [ 13 ].…”

Analysis of the Surgical Margins of the Oral Cancer using in Situ and Ex Vivo Fluorescence Spectroscopy

“…However our result, by analyzing these two moments, showed differences in fluorescence intensity and has kept only the shape of the spectra. An important observation to be discussed and studied better by the fact that in our study the ex vivo examination was performed immediately, after surgical removal of the specimen; at this time, the specimen is found in a state of ischemia-reperfusion and with alterations from metabolic cofactors when viewed in other tissues 35,[38][39][40] .…”