Genotyping strategies for tissues fixed with various embalming fluids for human identification, databasing, and traceability

Madeline Ashton; Natalia Czado; Michelle Harrel; Sheree Hughes

Abstract

Within anatomical willed body programs and skeletal collections, whole bodies and their disassociated limbs and organs are identified and tracked. However, if these tracking mechanisms fail, DNA recovered from the formalin‐fixed tissues/organs could provide an additional layer of quality assurance. Embalming fluids preserve biological tissues; however, they also damage, fragment, and cross‐link DNA and protein molecules. This project investigated the success of STR‐typing from various soft tissue and bone samples that were fixed with embalming solutions with a range of formaldehyde concentrations. Formalin‐fixed samples dissected from five cadavers, including skin, muscle, bone, heart, and kidney were used in Phase 1 of this study. In Phase 2, an additional 57 tissue samples from various embalmed organs and body parts were collected to demonstrate long‐term fixation and direct applicability within a body donor program. DNA was extracted from the samples using the QIAamp® FFPE Tissue Kit (QIAGEN), quantified with the Investigator® QuantiPlex® Pro RGQ qPCR Kit (QIAGEN), and amplified using the Investigator® 24plex and 26plex QS Kits and the Investigator® DIPplex Kit (QIAGEN). The results show the DNA was severely damaged, degraded, and often in low amounts (after one year post‐embalming). Sampling from skin and muscle tissues embalmed with ~2.5%–5% formaldehyde solutions appears to be the best strategy for identification, while also maintaining the preservation of the tissues. The results of this project can provide informative data when determining which genotyping strategy may be best suited for the identification, re‐association, and establishment of a database for the provenance of formalin‐fixed human remains.