Evaluation of Sibling-Ship Analysis in Secluded Lebanese Villages with Increased Mating Patterns

DNA profiling and statistical analysis in kinship studies aim to quantify the potential source of a biological trace or its possible relatedness with another trace. When parentage testing is not possible, another relatedness testing, such as sibling-ship analysis, could be helpful. The discrimination power of DNA analysis for sibling-ship, compared to cases of parentage analysis, is relatively low even in populations with homogeneous gene flow. The Lebanese population has a marked geographical and social structure, where endogamy1 amounts to an average of 88% and consanguinity2 reaches 31%, which lowers STR diversity and the discrimination power of sibling-ship statistical assessment. To assess the effect of mating patterns between individuals residing in rural and/or secluded Lebanese villages on sibling-ship analysis, six Lebanese villages with high rate of endogamy and consanguinity, representative of the majority of Lebanese villages, were targeted. Profiles were established using PowerPlex 16HS, PowerPlex ESI17 and PowerPlex CS7 kits (Promega Corporation; Madison, WI, USA). Comparisons were conducted between each individual and all the other sampled individuals in the same village, using dedicated in-house software. Simulations involved different number of genetic systems (15,23 and 28 STR loci). Half and full sibling-ship simulations were performed among unrelated pairs in addition to simulations among related individuals that were used as controls. Adventitious matches in both half and full sibling-ship simulations were observed. Increasing the number of systems from 15 to 23 and to 28 served in decreasing risk of false inclusions. These results highlight the significance of potential errors relative to relationship DNA testing when social and/or geographical seclusion is disregarded in the Lebanese population or in populations with high rates of endogamy and consanguinity practices