Improving complex kinship analyses with additional STR loci

Abstract

In a standard paternity testing, mother, child, and alleged father are analyzed with STR markers using commercially available kits. Since Italian civil legislation does not have thresholds to confirm a paternity, paternity is practically proven when likelihood ratio increases prior probability of paternity to posterior, accepted by court as sufficient. However, in some cases the number of markers included in a commercial kit may be insufficient to conclusively prove or disprove a relationship between individuals, especially when complex family scenarios are suspected or indirect analyses are required. Additional genetic information can increase the values of the likelihood ratio regarding the detection of true parental relationships in a pedigree, while reducing the chances of false attributions (e.g. false paternities). In these cases the introduction of a 26Plex amplification system allows to examine 23-26 additional markers depending on the commercial kit used, thus increasing the statistical power of the kinship analysis. The PCR conditions were optimized for a multiplex amplification system and a new generation CE instrument. In order to demonstrate the utility of additional STRs markers, four complex kinship cases are presented.

Comparison of Two Different Multiplex Systems in Calculating Kinship Among Close Relatives

“…Studies suggest that genotyping more than 20 autosomal STR loci improve forensic personal identification, especially in the sibship analyses (Allen et al, 2007;Carboni et al, 2014;Von Wumb-Schwark et al, 2015;Tamura et al, 2015;Turrina et al, 2016), which corresponds to our findings.…”

“…The introduction of additional seven loci used in the PowerPlex ® Fusion System increased the values of LR in 5 out of 7 analyzed pairs. Carboni et al (2014) reported a case study of two women who were cousins and they suspected to be daughters of the same father. Their mothers were sisters and were not available for kinship testing.…”

Genetic polymorphism of 22 autosomal STR markers in a Han population of Southern China

“…However, supplementary STRs are required to significantly evaluate pairwise, distant and/or complex relationships [3][4][5]. Additionally, additional STRs may be needed to confirm paternity in cases in which genetic mutations occur between the parents and progeny [6], null alleles are present [7] or a relative of an alleged father is involved [8][9][10].…”

Potential of 13 linked autosomal short tandem repeat loci in pairwise kinship analysis

“…Although X‐chromosomal, Y‐chromosomal STRs, or mtDNA can be helpful for kinship analysis, these markers only can be applied to particular cases and their discrimination powers are relative small owing to their unique genetic behaviors . Autosomal STR markers are necessary to solve the kinship problems . Additionally, linked autosomal markers are required to differentiate the second‐degree relationships (e.g.…”