Simulation of Human Identification Using DNA From Formalin-Fixed and Paraffin-Embedded (FFPE) Cancer Tissue as a Reference Sample

Archived slides of formalin-fixed and paraffin-embedded (FFPE) tissues are often the only source of DNA available for the identification of a deceased person. Difficulties may arise when FFPE tissue from a malignant tumor is used. We performed a simulated identification of human remains to estimate how useful the use of such type of samples would be in a real-life scenario. Tissue samples obtained from a patient with clear cell ovarian carcinoma were processed according to standard histopathological procedures. Nine years later, three slides (representing reference samples of a missing person) were selected: one containing only healthy tissue, one with a mixture of healthy and cancerous tissue, and one with only cancerous tissue. A saliva swab (representing a sample of found human remains) was obtained from the patient. A short tandem repeat (STR) profile was obtained from the samples. Healthy tissue showed a complete loss of two alleles. The mixture of healthy and cancerous tissue showed a complete loss of three alleles. The complete genetic profile of the sample containing only cancerous tissue was obtained, which matched all alleles with the one obtained from saliva. None of the tissue samples showed the presence of additional alleles. The findings presented in this work indicate that, in some cases, FFPE samples containing cancerous tissue could be used as reference samples in the genetic identification of human remains. However, caution should be exercised when abnormalities are present that could complicate the identification process, such as a complete loss of alleles or the presence of additional alleles.