X chromosomal recombination—a family study analysing 39 STR markers in German three-generation pedigrees

Abstract

Typing of polymorphisms on the human chromosome X (ChrX) has become a standard technique in forensic genetics, and a growing number of short tandem repeats (STRs) has been established. Knowledge of marker recombination is of great significance especially when ChrX typing is used in forensic kinship testing. It is known that meiotic recombination is not a simple function of physical distance but crossing over events tend to be clustered. Information on genetic distances between markers can be gathered by family studies and by interpolation of gene bank data such as the Rutgers map. We typed DNA samples of pedigrees consisting of mothers with several sons and grandfather-mother-son constellations and report here the recombination characteristics of 39 ChrX STRs in up to 135 meioses.

X chromosomal recombination—A family study analyzing 26 X‐STR Loci in Chinese Han three‐generation pedigrees

“…Significant linkage between HPRTB and DXS8377 is observed with a maximum LOD score of 2.959. This result is not in agreement with the results by Hering et al , where linkage complete independent segregation between HPRTB and DXS8377 was shown.…”

“…Similar results are obtained within the region from DXS6807 (4.74 Mb) to DXS9902 (15.32 Mb). The pattern of linked marker groups is similar to that reported by Hering et al . Significant linkage marker pairs also can be observed within the block from DXS7424 (100.61 Mb) to GATA31E08 (140.23 Mb) with the exception of combinations of DXS7133/DXS6854 and DXS7133/HPRTB.…”

“…Recombination rate (θ) is necessary for calculation of the LRs when linked markers on the same chromosome are used to analyze relationship. In comparing θ s computed from our family samples with those estimated from European families, such as Germans , Italian , Greenlanders, Danes, and Somalis , and European and Asian , our results are in agreement with European and Asian , German except DXS8377‐DXS7423, Italian except DXS6809‐DXS6789, Greenlanders, Danes, and Somalis except DXS10079‐DXS10074. But the θ s of DXS7132‐DXS10079, DXS10079‐DXS10074, DXS10074‐DXS10075, DXS6809‐DXS6789, and DXS7424‐DXS101 from HapMap are below the lower limit of 95% CIs of our studied results.…”

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

“…All intra-group genetic distances were reported to be well below 1 cM. In order to validate these figures, and to facilitate reliable use of X-STRs in practical kinship analysis, we choose to expand the existing German family data [15] into an international collaborative study.…”

“…Recently, two studies [13,14] strongly suggested that our abovementioned rough and preliminary estimates of the recombination fractions between the Argus X-8 markers needed to be modified. This led us to publish the recombination pattern of 39 X-STRs as observed in German three-generation families, comprising a total of 135 meioses [15]. However, since the accuracy of the recombination fraction estimates ensuing from such analyses is critically dependent upon the number of meioses studied, we choose to expand upon the aforementioned German study.…”