The influence of the different mutation models in kinship evaluation

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Different mutation models have been developed considering the genotypic observations of parent(s)/offspring duos or trios, even though, for autosomal transmission, only Mendelian incompatibilities, not mutations, are able to be identified. The most commonly considered mutation models are the so-called “Equal”, “Proportional”, “Stepwise” and “Extended Stepwise”, all implemented in the software Familias.In this work we simulated 100,000 profiles (duos and trios) of parent-child, full-siblings, and half-siblings, assuming a specific database for 17 autosomal STRs and probabilities of incompatibility inferred from the American Association of Blood Banks (AABB) report, 2008. Using the R version of the software Familias, we calculated the likelihood ratios where the probability of the genotypic configuration of the individuals assuming each of the pedigrees was compared with the probability of the same observations assuming unrelatedness. In the case of full-siblings, the comparison assuming half-sibship as the alternative pedigree was also considered. The results show that for profiles generated assuming the above mentioned pedigrees, except for unrelated, the use of different mutation models with parameters inferred from the proportion of observed mendelian incompatibilities does not result in major differences, which also indicates that the consideration of hidden mutations does not have a major influence in the final result.Future work should be developed to measure the impact for cases where a close relative of the father, such as a brother, is analyzed as the putative father in a standard paternity test.