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Formalin-fixed and paraffin-embedded tissue (FF-PET) is an invaluable resource for retrospective molecular genetic studies, but the extraction of high-quality genomic DNA from FF-PET is still a problematic issue. Despite the range of DNA extraction methods currently in use, the association of phenol-chloroform extraction and silica-based purification protocols, reported in ancient DNA studies on archaeological bones, has, to our knowledge, not been used for DNA extraction from FF-PET yet. The present study compared the efficiency of three DNA extraction and purification protocols from two different FF-PET substrates, heart and liver, by using quantitative PCR and multiplex amplification. We showed that the method, using phenol-chloroform and the QIAamp DNA mini Kit (Qiagen), was the most effective DNA extraction and purification method and that the DNA quantity extracted from liver is statistically more important than that extracted from heart. Autosomal STR typing by multiplex amplifications gave partial allelic profiles with only small size products (less than 300 bases) amplified, suggesting that DNA extracted from FF-PET was degraded. In conclusion, the protocol presented here, previously described in studies on ancient bones, should find application in different molecular studies involving FF-PET material.

Genetic testing for cardiac channelopathies in sudden unexplained death (SUD) has developed substantially over the last years. The Next Generation Sequencing (NGS) technology provides an unprecedented opportunity to screen for genetic variations underlying arrhythmogenic genes in a short period of time at a low cost. The present study aimed to perform genetic testing with NGS technologies on the Ion Torrent Personal Genome Machine™ (Ion PGM™) sequencer, in targeting a total of 23 genes reported to be associated with inherited cardiac channelopathies in order to identify the possible cause of death in a cohort of post-mortem cases. The molecular analyses focused on 16 cases of SUD, aged less than 35 years old. In all cases, the cause of death could not be determined after a rigorous autopsy associated with histopathological and toxicological analyses according to the guidelines of the Association for European Cardiovascular Pathology. DNA was extracted from fresh frozen tissue. An average of 200 variants was identified per case. However, after the prioritization process using a new scoring program (VaRank) and after the conjunction of clinical data and molecular findings, four “likely pathogenic” variants (including two undescribed variants), were identified in three cases (18.75%) of our cohort in the genes KCNH2 , ANK2 , SCN5A and RYR2 . One case, who died during psychiatric hospitalization after administration of a QT prolonging drug, showed a double “likely pathogenic” variant in Long QT genes ( ANK2 and SCN5A ) which may have predisposed to drug-induced cardiac arrhythmias. Our study illustrates that the NGS approach based on AmpliSeq™ libraries and Ion Torrent PGM™ sequencing may be an efficient approach, integrated to post-mortem examination. Given the massive amount of information generated by NGS, a rigorous filtration strategy of variants coupled with multidisciplinary collaboration is crucial to determine the potential pathogenic role of identified variants in the cause of death.