DNA analysis of abortion material assisted by histology screening

Analysis of aborted fetal material using autosomal STR markers in forensic cases of sexual assault

Sexual violence represents a widespread social problem associated with serious lifelong consequences. In many cases, an outcome of sexual violence is the victim's unwanted pregnancy, usually ended in an abortion. The objective of this paper is to report five rape cases, including rapes of a minor and young woman, two incest cases and a case of human trafficking for sexual exploitation, where every case resulted in the victim's pregnancy. In each case, pregnancy was terminated in the first trimester or at the beginning of the second trimester in the relevant medical center or clinic. Fresh fetal blood or aborted tissue samples were delivered to our laboratory in order to perform paternity testing for the purpose of proving the crime. DNA extraction using Qiagen Dneasy™ Tissue Kit was optimized according to the sample type. Amplification of autosomal STR (Short Tandem Repeat) markers was performed using the PowerPlex®16 System. In two cases, mixtures of maternal and fetal DNA in the aborted fetal material were found. Using the LRmix Studio v.2.1.5 Software for interpreting DNA mixtures based on a probabilistic model, the likelihoods of maternal contribution and presence of fetal allelic variants inherited from the alleged father/suspect were calculated. Based on these results, we confirmed the presence of assumed fetal fractions (determined before software analysis) in the mixtures. In all cases, positive paternity proved the crime (probabilities of paternity >99.9999%). This cases report once again pointed out the importance of DNA analysis in the process of clarifying and solving forensic cases and demonstrated that the LRmix Studio v.2.1.5 Software can deal with complex cases such as sexual assaults.

Forensic DNA expertise of incest in early period of pregnancy

Proving incest from tissue obtained by abortion early in pregnancy can be a challenge. Problems include the small quantity of embryonic tissue in the products of conception, and the mixing of DNA from mother and embryo. In many cases, this amorphous material cannot be grossly segregated into maternal and fetal components. Thus, morphological discrimination requires microscopy to select relevant tissue particles from which DNA can be typed. This combination of methods is reliable and efficient. In this article, we present two cases of incest discovered by examination of products of conception.

Incestuous Paternity Detected by STR-typing of Chorionic Villi Isolated from Archival Formalin-fixed Paraffin-embedded Abortion Material Using Laser Microdissection

Microscopic examination of a blood clot expelled by a physically and mentally disabled woman taken to the emergency room because of genital bleeding revealed the presence of chorionic villi encircled by decidua, hemorrhage, and necrosis. In order to identify the father of the product of conception, sections of formalin-fixed, paraffin-embedded abortion material were subjected to laser microdissection: DNA extraction from chorionic villi selectively isolated from the surrounding tissues allowed successful STR-typing of fetal cells, which was otherwise prevented by excess maternal DNA. The large number of homozygous genotypes in the fetal profile suggested incestuous paternity. Analysis of reference DNA samples from male relatives excluded the woman's father, paternal grandfather, and maternal grandfather, whereas the obligate paternal alleles of the fetus were constantly present in the genotypes of the woman's brother, clearly demonstrating brother-sister incest (probability of paternity > 99.99999%).