Highlights
- •Improved recombination rate estimates for X STRs.
- •Multi-core parallelization of a likelihood-based estimation approach.
- •Corroboration of previous studies rejecting a simple linkage group model of X STRs.
Abstract
Typing of X chromosomal short tandem repeat (X STR) markers has become a standard
element of human forensic genetic analysis. Joint consideration of many X STR markers
at a time increases their discriminatory power but, owing to physical linkage, requires
inter-marker recombination rates to be accurately known. We estimated the recombination
rates between 15 well established X STR markers using genotype data from 158 families
(1041 individuals) and following a previously proposed likelihood-based approach that
allows for single-step mutations. To meet the computational requirements of this family-based
type of analysis, we modified a previous implementation so as to allow multi-core
parallelization on a high-performance computing system. While we obtained recombination
rate estimates larger than zero for all but one pair of adjacent markers within the
four previously proposed linkage groups, none of the three X STR pairs defining the
junctions of these groups yielded a recombination rate estimate of 0.50. Corroborating
previous studies, our results therefore argue against a simple model of independent
X chromosomal linkage groups. Moreover, the refined recombination fraction estimates
obtained in our study will facilitate the appropriate joint consideration of all 15
investigated markers in forensic analysis.
Graphical abstract

Graphical Abstract
Keywords
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Article info
Publication history
Published online: July 23, 2016
Accepted:
July 7,
2016
Received in revised form:
May 27,
2016
Received:
January 20,
2016
Identification
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© 2016 Elsevier Ireland Ltd. All rights reserved.