Since two and a half decades, in human identification, the short tandem repeat (STR) markers represent the “gold standard.” Besides them, haploid markers such as X-STR and Y-STR are also used to complement the autosomal markers. In human identification, DNA from body fluids, especially saliva, represents an important tool. The aim of this chapter is to present the importance of analyzing X-STR markers in a relatedness case between a sister and her presumptive brother, a carbonized victim using body fluids for their DNA identification. Our laboratory had to establish the relatedness between a woman and her presumptive brother (PB), who was the victim of a car accident explosion. In this case, as reference sample we used saliva collected on swabs from the woman and blood sample from the deceased victim. For the DNA extraction, DNA IQ Casework (Promega, USA) was used. DNA quantification was done with PowerQuant System kit (Promega, USA). Furthermore, the DNA samples were amplified with Investigator 24plex QS (Qiagen, Germany) for the STR markers and Investigator Argus 12-X QS kit (Qiagen, Germany) for the X-STR markers. The amplified DNA products were separated by capillary electrophoresis on a 3500 Genetic Analyzer. In this case, full genetic profiles were obtained for the woman and her presumptive brother on both STR and X-STR markers. Thus, we could confirm a full sibling relationship between them. Since the introduction of DNA in human identification, it represents a useful tool in establishing sibling relationship from different biological samples.
Part of the book: Saliva and Salivary Diagnostics