Variation of X-chromosomal microsatellites in Belarus within the context of their genetic diversity in Europe.

More and more X-STR data are becoming available for worldwide human populations for forensic and anthropological investigations, but the European datasets analysed so far represent mainly the central, northern, western and southern part of the continent with populations of Eastern Europe being practically uninvestigated. In the present study, we assessed genetic variation and linkage disequilibrium of 19 X-chromosomal STR markers (DXS7132, DXS7133, DXS7423, DXS7424, DXS8377, DXS8378, DXS9895, DXS10074, DXS10075, DXS10079, DXS10101, DXS10103, DXS10134, DXS10135, DXS10146, DXS10147, DXS10148, GATA172D05, HPRTB) in four regional populations of an Eastern European state of Belarus, including 12 loci incorporated in the Argus X-12 kit. Our results revealed cumulative power of discrimination of the tested X-STR loci to amount to 0.999999999999996 and 0.999999997 in females and males, respectively. Analysis of molecular variance demonstrated regional stratification within the country, excluding the use of a common X-STR database for Belarus in forensic casework. However, development of a separate X-STR database for the northwestern part of the country or exclusion of four loci displaying regional differences from the dataset were shown to eliminate the observed geographic substructure among Belarusians. Comparison of the Belarusian genotypes with X-STR data from other European populations disclosed a geography-driven northeast-southwest gradient extending from Belarus and Finland to Iberia and Italy. This study is the first extensive report on variation of X-STR markers in populations from Eastern Europe and the first comprehensive analysis of diversity of X-chromosomal microsatellites in Europe.