DXS10079, DXS10074 and DXS10075: new alleles and SNP occurrence

The number of established X-chromosomal STR markers suitable for forensic usage has risen continuously during recent years. The observation of X-chromosomal transmission lines can significantly contribute to the solving of complex kinship cases. The highly polymorphic tetranucleotide markers DXS10079, DXS10074 and DXS10075 are located within a 280 kb region at Xq12 and provide stable haplotypes. Most of these haplotypes occur at low frequencies in the German population, which would qualify this marker cluster as a useful tool in pedigree analysis. For routine use it is necessary to investigate the allele structure and check for variations in the repeat flanking region in samples of different ethnic populations. The information on SNP occurrence may help to minimise pitfalls caused by partial primer mismatching. We sequenced a variety of samples from Germans, Asians and Africans with respect to different STR alleles. For all three marker systems SNPs were detected in the repeat flanking regions. Some alleles found in the marker systems DXS10074 and DXS10075 exhibited typical repeat structures and SNP patterns found only in Africans and differing from Germans and Asians. The highest SNP diversity for DXS10079 was present in samples of all three ethnic groups. Further population data are needed to confirm this observation.