X-chromosome analysis in an unusual deficiency maternity case

The X-chromosome (X-Chr) markers are more efficient than autosomes in special cases of kinship analysis. Here, we show an unusual case, where two half-sisters (AR, AP), daughters of the same woman (AL), wanted to know whether they were also half-sisters of two other women (MM, MS) and a man (CR). These latter subjects were known to be children of different fathers. DNA was also available from AR's and AP's maternal aunt AA. Using the undisputed relationships (AA being aunt of the half-sisters AR and AP), the X-haplotypes of AR's and AP's maternal grandparents could be inferred. Grandmother's X-haplotypes were also shared by MM, MS and CR, thus supporting hypothesis 1. A Mendelian inconsistency was observed at locus DXS10134, though it could not be distinguished between mutation and intra cluster recombination. Extra cluster meiotic recombination events were also observed, as some other interesting outcomes useful for forensic genetics discussion. According to ISFG guidelines [1,2] the biostatistical evaluation in kinship analysis was based on a likelihood ratio approach, using FamiLinkX and Familias programs respectively on the X-chromosome and autosomes analysis. [3–5]