Determining factors for obtaining DNA profiles in biological samples of Spanish civil war victims (1936-1939)

The identification of victims from the Spanish Civil War (1936-1939) has been a subject of historical research and familial interest in locating lost relatives since the late twentieth century in Spain. Acquiring well-preserved postmortem samples from these individuals is crucial for subsequent genotyping and identification, and this proves challenging with low-template DNA samples. Through the utilization of the GlobalFiler™ IQC PCR Amplification Kit (Thermo Fisher Scientific) in 490 samples from 245 cadaveric individuals, we have conducted a study on factors that may affect or serve as indicators of the quality of the autosomal electropherogram and the effectiveness of obtaining a complete reliable profile. The most significant factor in the samples has proven to be the site of extraction, namely, the archaeological sites. The conservation of the samples has been positively and negatively influenced by environmental conditions. Regarding the type of sample, we obtained better results in dental samples than in bones, and when only bones were able to be used, the phalanges produced better results in complete profiles, except for the petrous portion of the temporal bones, which were carried out in a very poorly preserved site. Concerning the obtained electropherograms, the presence of artifacts (stutters), has been analyzed as an indicator of profiles with an acceptable quantity and quality of DNA, in contrast to the presence of drop-outs, which are associated with the impossibility of obtaining a complete profile.