Potentials and limits of pairwise kinship analysis using autosomal short tandem repeat loci

Abstract

At least in principle, most instances of complex kinship testing can be reduced to pairwise kinship cases involving two critical family members that either link or separate presumed sub-branches of a family. In the European population, the 34 short tandem repeats (STRs) currently used in forensic genetics are sufficiently powerful to allow assessment of disputed first and second but not lower degrees of pairwise blood relatedness. We provide estimates of the means and variances of marker-specific log-likelihood ratios, using large-sample approximation and assuming different scenarios of pairwise kinship analysis. These estimates allow power calculations to be performed for any combination of the available STRs. Since some of the markers considered are physically linked, chromosome-wide likelihood calculations in kinship cases other than parent-child duos (and trios) have to take the reduced rates of meiotic inter-marker recombination into account. We show by simulation that this requirement may be ignored when discriminating distant hypotheses about kinship, but that linkage may play an important role in the biostatistical analysis of more intricate cases.

Collaborative genetic mapping of 12 forensic short tandem repeat (STR) loci on the human X chromosome

“…As has been demonstrated many times before, exact likelihood calculation in kinship testing with physically linked markers requires the consideration of both linkage and linkage disequilibrium (LD), not only for the X chromosome [1,6,12,13], but in general [25]. The computational relevance of the two characteristics is a function of their actual tightness and strength, which implies that it may be admissible to numerically treat very loosely linked makers (or groups of markers) as if they were located on different chromosomes.…”

Mutation analysis of 24 short tandem repeats in Chinese Han population

“…The most commonly used STRs are the loci included in the commercially available amplification kits, such as AmpFlSTR® Identifiler (Applied Biosystems, Inc., Foster City, CA, USA) and PowerPlex® 16 System (Promega Corp., Madison, WI, USA). But, extended loci may be needed in parentage testing, especially in deficiency cases of disputed paternity [1] and complex kinship testing [2,3]. Additional STRs have been developed for such purpose [4,5].…”

Exclusion probabilities and likelihood ratios with applications to mixtures

“…The asymptotic lognormal approximation discussed in [12] worked reasonably well for 14 markers (details omitted) and is expected to improve for a larger number of markers. We choose the number of markers so that the power is comparable to the Figure 8 shows the results.…”