Forensic science technique applied for calculation of kinship index

Implementing conservation strategies needs the knowledge of relationships inside the concerned population. The aim of this study was to find tools to help scientists and breeders to manage endangered populations or populations with missing pedigree information. The animal genetics literature often seems unaware of relevant developments in human genetics (and conversely). In this study, an approach called Familial Searching was tested. This is used in forensic science, in addition to matching DNA evidence directly to criminal profiles, to search for people (present in a database) who are related to an individual that left DNA evidence at a scene of crime. This method is based on the calculation of likelihood ratios (LR) between genotype of an individual and genotypes of each other individuals of the database. In order to decrease the number of comparisons, the available pedigree information was used as ‘local’ prior information, i.e. relating to specific pairs of individuals. General knowledge about the studied population (e.g., generation interval, sexual maturity) was considered as ‘global’ prior information. Including prior information reduced the number of comparisons from over 50%. Results showed that the parents were always classified into the 4 highest LR. This method simplified parentage verifications, it allowed the detection of 90% of false parentage (LR=0). It also allowed to create new links in the pedigree through detection of unregistered parents. The method was tested on the Skyros pony, an indigenous Greek breed. For this breed, partial pedigree information was available, and 99 individuals were genotyped at 16 microsatellite loci. The method allowed to check about 2500 possible parent-child combinations, three registered parentages were considered as incorrect and one non-recorded parentage was detected. The method will now be tested on other breed and with other markers, e.g. SNPs.