DXS6797 contains two STRs which can be easily haplotyped in both sexes

X-chromosomal markers: past, present and future

Experience gained in clinical genetics led to the fundamental idea of using X-chromosomal markers in a wide range of forensic applications. To date more than 30 STRs have been established as forensic markers. Joint typing of very tightly linked STRs yields stable haplotypes, and can be used for establishing the relationship between distant relatives, such as aunt-niece pairs and cousins. For such applications the new ChrX typing kit Argus X-8 which is commercially available now is a powerful tool. This paper is aimed at presenting a brief survey of historical developments and discussing present and future aspects of forensic X-chomosomal testing.

Japanese population data for eight X-STR loci using two new quadruplex systems

Using two new X-chromosome short tandem repeats (X-STR) multiplex (quadruplex) systems, we investigated Japanese population data (drawn from 401 individuals) for eight X-STR loci (DXS10011, DXS9898, DXS8377, HPRTB, DXS7132, DXS6797, GATA172D05, and DXS6807). Allele typing with the systems was successful for all loci. The combined powers of discrimination of the eight loci in men and women were 0.999997 and 0.9999999996, respectively. We conclude that combined analyses of the eight X-STR loci using these two quadruplex polymerase chain reaction systems represent a powerful tool for Japanese forensic practice.

DXS10079, DXS10074 and DXS10075 are STRs located within a 280-kb region of Xq12 and provide stable haplotypes useful for complex kinship cases

The evaluation of the short tandem repeat (STR) markers DXS10079, DXS10074 and DXS10075 was amended to establish a STR cluster spanning a genetic distance<1 cM. These three STRs are located within a 280-kb region at Xq12 and provide stable haplotypes useful for solving complex kinship cases. Theoretically, this cluster could give rise to 2,548 different haplotypes in the German population and the genotyping of 781 men revealed the presence of 172 haplotypes. Since the three STRs were shown to be in strong linkage disequilibrium (LD), haplotype frequencies cannot be computed on the basis of a single locus allele frequency alone but have to be estimated directly. Here, we present data on linkage, haplotype frequencies and LD in a German population. Further clusters from other regions of the X chromosome will be published in the future to cover the chromosome with a well-structured network of highly informative sites.