Informatividad a posteriori en casos de paternidad estándar con el kit Investigator Argus X-12 y hallazgos mutacionales

Abstract

IntroductionThe Investigator Argus X-12 kit is a valuable complementary tool for human identification purposes, especially for solving complex kinship cases. The analysis of these cases generates valuable information in routine forensic work, such as a posteriori informativeness (LR: likelihood ratio) and mutation rates. ObjetiveTo analyze the LR offered by the Argus X-12 QS kit in 74 Mexican families, including the father, mother, and daughter(s), respectively. MethodsExact LRs were estimated with the FamlinkX software in the families as paternity trio cases (n= 74; average 8.E+14) and duo cases (n= 148; average 6.1E+11), omitting the mother and father, respectively. ResultsThe LR of the trios (a posteriori) was significantly higher than the -a priori- parameter IP typical (3.98E+04). As reference, we report the LR of complex kinship cases solved with X-STRs: maternal half-sisters (LR= 111), paternal half-sisters (LR= 5567), paternal half-sisters with their mothers (LR= 6.0E+07, and paternal grandmother-granddaughter (LR= 15,864). Nine mutations were detected in 161 meiosis. The mutation rate was estimated in seven X-STRs, which was 0,0062 (1/161) for DXS10148, DXS10135, DXS8378, DXS10146, and DXS7423, and 0,0124 (2/161) for DXS10074 and DXS10101. These findings will be useful in future meta-analyses to achieve more conclusive estimates. A null allele in DXS10148 was inferred between a mother and daughter, supported by the low probability that the finding is explained by an 8-step mutation (26.1→18), and the low frequency of the 26.1 homozygote. ConclusionThe a posteriori informativeness of Argus X-12 in paternity and kinship cases described herein, justify the inclusion of the X-STRs in forensic genetics labs.